diff --git a/.idea/detekt.xml b/.idea/detekt.xml
new file mode 100644
index 0000000..d6df3a4
--- /dev/null
+++ b/.idea/detekt.xml
@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="DetektProjectConfiguration">
+    <enableDetekt>true</enableDetekt>
+    <enableAllRules>true</enableAllRules>
+    <treatAsError>true</treatAsError>
+    <rulesPath>$PROJECT_DIR$/code_quality_tools/detekt.yml</rulesPath>
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/jarRepositories.xml b/.idea/jarRepositories.xml
index fdc392f..b3e9cbd 100644
--- a/.idea/jarRepositories.xml
+++ b/.idea/jarRepositories.xml
@@ -16,5 +16,10 @@
       <option name="name" value="MavenRepo" />
       <option name="url" value="https://repo.maven.apache.org/maven2/" />
     </remote-repository>
+    <remote-repository>
+      <option name="id" value="BintrayJCenter" />
+      <option name="name" value="BintrayJCenter" />
+      <option name="url" value="https://jcenter.bintray.com/" />
+    </remote-repository>
   </component>
 </project>
\ No newline at end of file
diff --git a/build.gradle b/build.gradle
index 4b5664a..e125d8f 100644
--- a/build.gradle
+++ b/build.gradle
@@ -6,9 +6,10 @@ buildscript {
 }
 
 plugins {
-    id 'org.jetbrains.kotlin.jvm' version '1.4.30-M1'
+    id 'org.jetbrains.kotlin.jvm' version '1.4.21'
     id 'info.solidsoft.pitest' version '1.5.2'
     id 'maven'
+    id "io.gitlab.arturbosch.detekt" version "1.14.1"
 }
 
 group 'com.github.asm0dey'
@@ -16,10 +17,11 @@ version '1.0-SNAPSHOT'
 
 repositories {
     mavenCentral()
+    jcenter()
 }
 
 dependencies {
-    implementation "org.jetbrains.kotlin:kotlin-stdlib"
+    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
     implementation 'com.fasterxml.woodstox:woodstox-core:6.2.3'
     testImplementation "io.kotest:kotest-runner-junit5:$kotest_version"
     testImplementation "ch.tutteli.atrium:atrium-infix-en_GB:$atrium_version"
@@ -45,3 +47,14 @@ pitest {
     outputFormats = ['XML', 'HTML']
     avoidCallsTo = ["kotlin.jvm.internal", "kotlinx.coroutines"]
 }
+
+detekt {
+    parallel = false
+    config = files "code_quality_tools/detekt.yml"
+    reports {
+        xml { enabled = true }
+        html { enabled = true }
+    }
+}
+
+tasks.detekt.jvmTarget = "1.8"
\ No newline at end of file
diff --git a/code_quality_tools/detekt.yml b/code_quality_tools/detekt.yml
new file mode 100644
index 0000000..e9b9817
--- /dev/null
+++ b/code_quality_tools/detekt.yml
@@ -0,0 +1,617 @@
+comments:
+  active: true
+  AbsentOrWrongFileLicense:
+    active: false
+    licenseTemplateFile: 'license.template'
+  UndocumentedPublicClass:
+    active: true
+    searchInNestedClass: true
+    searchInInnerClass: true
+    searchInInnerObject: true
+    searchInInnerInterface: true
+  UndocumentedPublicFunction:
+    active: true
+  UndocumentedPublicProperty:
+    active: true
+
+complexity:
+  active: true
+  ComplexCondition:
+    active: true
+    threshold: 4
+  ComplexInterface:
+    active: true
+    threshold: 10
+    includeStaticDeclarations: false
+    includePrivateDeclarations: false
+  ComplexMethod:
+    active: true
+    threshold: 15
+    ignoreSingleWhenExpression: false
+    ignoreSimpleWhenEntries: false
+    ignoreNestingFunctions: false
+    nestingFunctions: [run, let, apply, with, also, use, forEach, isNotNull, ifNull]
+  LabeledExpression:
+    active: true
+    ignoredLabels: []
+  LargeClass:
+    active: true
+    threshold: 400
+  LongMethod:
+    active: true
+    threshold: 60
+  LongParameterList:
+    active: true
+    functionThreshold: 6
+    constructorThreshold: 7
+    ignoreDefaultParameters: false
+    ignoreDataClasses: true
+    ignoreAnnotated: []
+  MethodOverloading:
+    active: true
+    threshold: 10
+  NestedBlockDepth:
+    active: true
+    threshold: 4
+  ReplaceSafeCallChainWithRun:
+    active: true
+  StringLiteralDuplication:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    threshold: 3
+    ignoreAnnotation: true
+    excludeStringsWithLessThan5Characters: true
+    ignoreStringsRegex: '$^'
+  TooManyFunctions:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    thresholdInFiles: 30
+    thresholdInClasses: 11
+    thresholdInInterfaces: 11
+    thresholdInObjects: 11
+    thresholdInEnums: 11
+    ignoreDeprecated: false
+    ignorePrivate: false
+    ignoreOverridden: false
+
+coroutines:
+  active: true
+  GlobalCoroutineUsage:
+    active: true
+  RedundantSuspendModifier:
+    active: true
+  SuspendFunWithFlowReturnType:
+    active: true
+
+empty-blocks:
+  active: true
+  EmptyCatchBlock:
+    active: true
+    allowedExceptionNameRegex: '_|(ignore|expected).*'
+  EmptyClassBlock:
+    active: true
+  EmptyDefaultConstructor:
+    active: true
+  EmptyDoWhileBlock:
+    active: true
+  EmptyElseBlock:
+    active: true
+  EmptyFinallyBlock:
+    active: true
+  EmptyForBlock:
+    active: true
+  EmptyFunctionBlock:
+    active: true
+    ignoreOverridden: false
+  EmptyIfBlock:
+    active: true
+  EmptyInitBlock:
+    active: true
+  EmptyKtFile:
+    active: true
+  EmptySecondaryConstructor:
+    active: true
+  EmptyTryBlock:
+    active: true
+  EmptyWhenBlock:
+    active: true
+  EmptyWhileBlock:
+    active: true
+
+exceptions:
+  active: true
+  ExceptionRaisedInUnexpectedLocation:
+    active: true
+    methodNames: [toString, hashCode, equals, finalize]
+  InstanceOfCheckForException:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+  NotImplementedDeclaration:
+    active: true
+  PrintStackTrace:
+    active: true
+  RethrowCaughtException:
+    active: false
+  SwallowedException:
+    active: true
+    allowedExceptionNameRegex: '_|(ignore|expected).*'
+  ThrowingExceptionFromFinally:
+    active: true
+  ThrowingExceptionInMain:
+    active: true
+  ThrowingExceptionsWithoutMessageOrCause:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    exceptions:
+      - IllegalArgumentException
+      - IllegalStateException
+      - IOException
+  ThrowingNewInstanceOfSameException:
+    active: true
+  TooGenericExceptionCaught:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    exceptionNames:
+      - ArrayIndexOutOfBoundsException
+      - Error
+      - Exception
+      - IllegalMonitorStateException
+      - NullPointerException
+      - IndexOutOfBoundsException
+      - RuntimeException
+      - Throwable
+    allowedExceptionNameRegex: '_|(ignore|expected).*'
+  TooGenericExceptionThrown:
+    active: true
+    exceptionNames:
+      - Error
+      - Exception
+      - Throwable
+      - RuntimeException
+
+formatting:
+  active: true
+  android: false
+  autoCorrect: true
+  AnnotationOnSeparateLine:
+    active: false
+    autoCorrect: true
+  AnnotationSpacing:
+    active: true
+    autoCorrect: true
+  ArgumentListWrapping:
+    active: true
+    autoCorrect: true
+  ChainWrapping:
+    active: true
+    autoCorrect: true
+  CommentSpacing:
+    active: true
+    autoCorrect: true
+  EnumEntryNameCase:
+    active: true
+    autoCorrect: true
+  Filename:
+    active: true
+  FinalNewline:
+    active: true
+    autoCorrect: true
+    insertFinalNewLine: true
+  ImportOrdering:
+    active: true
+    autoCorrect: true
+    layout: 'idea'
+  MaximumLineLength:
+    active: true
+    maxLineLength: 140
+  ModifierOrdering:
+    active: true
+    autoCorrect: true
+  MultiLineIfElse:
+    active: true
+    autoCorrect: true
+  NoBlankLineBeforeRbrace:
+    active: true
+    autoCorrect: true
+  NoConsecutiveBlankLines:
+    active: true
+    autoCorrect: true
+  NoEmptyClassBody:
+    active: true
+    autoCorrect: true
+  NoEmptyFirstLineInMethodBlock:
+    active: false
+    autoCorrect: true
+  NoLineBreakAfterElse:
+    active: true
+    autoCorrect: true
+  NoLineBreakBeforeAssignment:
+    active: true
+    autoCorrect: true
+  NoMultipleSpaces:
+    active: true
+    autoCorrect: true
+  NoSemicolons:
+    active: true
+    autoCorrect: true
+  NoTrailingSpaces:
+    active: true
+    autoCorrect: true
+  NoUnitReturn:
+    active: true
+    autoCorrect: true
+  NoUnusedImports:
+    active: true
+    autoCorrect: true
+  NoWildcardImports:
+    active: true
+  PackageName:
+    active: true
+    autoCorrect: true
+  ParameterListWrapping:
+    active: true
+    autoCorrect: true
+    indentSize: 4
+  SpacingAroundColon:
+    active: true
+    autoCorrect: true
+  SpacingAroundComma:
+    active: true
+    autoCorrect: true
+  SpacingAroundCurly:
+    active: true
+    autoCorrect: true
+  SpacingAroundDot:
+    active: true
+    autoCorrect: true
+  SpacingAroundDoubleColon:
+    active: false
+    autoCorrect: true
+  SpacingAroundKeyword:
+    active: true
+    autoCorrect: true
+  SpacingAroundOperators:
+    active: true
+    autoCorrect: true
+  SpacingAroundParens:
+    active: true
+    autoCorrect: true
+  SpacingAroundRangeOperator:
+    active: true
+    autoCorrect: true
+  SpacingBetweenDeclarationsWithAnnotations:
+    active: false
+    autoCorrect: true
+  SpacingBetweenDeclarationsWithComments:
+    active: false
+    autoCorrect: true
+  StringTemplate:
+    active: true
+    autoCorrect: true
+
+naming:
+  active: true
+  ClassNaming:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    classPattern: '[A-Z][a-zA-Z0-9]*'
+  ConstructorParameterNaming:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    parameterPattern: '[a-z][A-Za-z0-9]*'
+    privateParameterPattern: '[a-z][A-Za-z0-9]*'
+    excludeClassPattern: '$^'
+    ignoreOverridden: true
+  EnumNaming:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    enumEntryPattern: '[A-Z][_a-zA-Z0-9]*'
+  FunctionMaxLength:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    maximumFunctionNameLength: 30
+  FunctionMinLength:
+    active: false
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    minimumFunctionNameLength: 3
+  FunctionNaming:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    functionPattern: '([a-z][a-zA-Z0-9]*)|(`.*`)'
+    excludeClassPattern: '$^'
+    ignoreOverridden: true
+    ignoreAnnotated: ['Composable']
+  FunctionParameterNaming:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    parameterPattern: '[a-z][A-Za-z0-9]*'
+    excludeClassPattern: '$^'
+    ignoreOverridden: true
+  InvalidPackageDeclaration:
+    active: true
+    excludes: ['*.kts']
+    rootPackage: ''
+  MatchingDeclarationName:
+    active: true
+    mustBeFirst: true
+  MemberNameEqualsClassName:
+    active: true
+    ignoreOverridden: true
+  NonBooleanPropertyPrefixedWithIs:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+  ObjectPropertyNaming:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    constantPattern: '[A-Za-z][_A-Za-z0-9]*'
+    propertyPattern: '[A-Za-z][_A-Za-z0-9]*'
+    privatePropertyPattern: '(_)?[A-Za-z][_A-Za-z0-9]*'
+  PackageNaming:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    packagePattern: '[a-z]+(\.[a-z][A-Za-z0-9]*)*'
+  TopLevelPropertyNaming:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    constantPattern: '[A-Z][_A-Z0-9]*'
+    propertyPattern: '[A-Za-z][_A-Za-z0-9]*'
+    privatePropertyPattern: '_?[A-Za-z][_A-Za-z0-9]*'
+  VariableMaxLength:
+    active: false
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    maximumVariableNameLength: 64
+  VariableMinLength:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    minimumVariableNameLength: 2
+  VariableNaming:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    variablePattern: '[a-z][A-Za-z0-9]*'
+    privateVariablePattern: '(_)?[a-z][A-Za-z0-9]*'
+    excludeClassPattern: '$^'
+    ignoreOverridden: true
+
+performance:
+  active: true
+  ArrayPrimitive:
+    active: true
+  ForEachOnRange:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+  SpreadOperator:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+  UnnecessaryTemporaryInstantiation:
+    active: true
+
+potential-bugs:
+  active: true
+  Deprecation:
+    active: true
+  DuplicateCaseInWhenExpression:
+    active: true
+  EqualsAlwaysReturnsTrueOrFalse:
+    active: true
+  EqualsWithHashCodeExist:
+    active: true
+  ExplicitGarbageCollectionCall:
+    active: true
+  HasPlatformType:
+    active: false
+  IgnoredReturnValue:
+    active: true
+    restrictToAnnotatedMethods: true
+    returnValueAnnotations: ['*.CheckReturnValue', '*.CheckResult']
+  ImplicitDefaultLocale:
+    active: false
+  ImplicitUnitReturnType:
+    active: false
+    allowExplicitReturnType: true
+  InvalidRange:
+    active: true
+  IteratorHasNextCallsNextMethod:
+    active: true
+  IteratorNotThrowingNoSuchElementException:
+    active: true
+  LateinitUsage:
+    active: false
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    excludeAnnotatedProperties: []
+    ignoreOnClassesPattern: ''
+  MapGetWithNotNullAssertionOperator:
+    active: false
+  NullableToStringCall:
+    active: true
+  RedundantElseInWhen:
+    active: true
+  UnconditionalJumpStatementInLoop:
+    active: true
+  UnnecessaryNotNullOperator:
+    active: true
+  UnnecessarySafeCall:
+    active: true
+  UnreachableCode:
+    active: true
+  UnsafeCallOnNullableType:
+    active: true
+  UnsafeCast:
+    active: true
+  UselessPostfixExpression:
+    active: true
+  WrongEqualsTypeParameter:
+    active: true
+
+style:
+  active: true
+  ClassOrdering:
+    active: false
+  CollapsibleIfStatements:
+    active: false
+  DataClassContainsFunctions:
+    active: false
+    conversionFunctionPrefix: 'to'
+  DataClassShouldBeImmutable:
+    active: false
+  EqualsNullCall:
+    active: true
+  EqualsOnSignatureLine:
+    active: false
+  ExplicitCollectionElementAccessMethod:
+    active: false
+  ExplicitItLambdaParameter:
+    active: false
+  ExpressionBodySyntax:
+    active: false
+    includeLineWrapping: false
+  ForbiddenComment:
+    active: true
+    values: ['TODO:', 'FIXME:', 'STOPSHIP:']
+    allowedPatterns: ''
+  ForbiddenImport:
+    active: false
+    imports: []
+    forbiddenPatterns: ''
+  ForbiddenMethodCall:
+    active: false
+    methods: ['kotlin.io.println', 'kotlin.io.print']
+  ForbiddenPublicDataClass:
+    active: true
+    excludes: ['**']
+    ignorePackages: ['*.internal', '*.internal.*']
+  ForbiddenVoid:
+    active: false
+    ignoreOverridden: false
+    ignoreUsageInGenerics: false
+  FunctionOnlyReturningConstant:
+    active: true
+    ignoreOverridableFunction: true
+    excludedFunctions: 'describeContents'
+    excludeAnnotatedFunction: ['dagger.Provides']
+  LibraryCodeMustSpecifyReturnType:
+    active: true
+    excludes: ['**']
+  LibraryEntitiesShouldNotBePublic:
+    active: true
+    excludes: ['**']
+  LoopWithTooManyJumpStatements:
+    active: true
+    maxJumpCount: 1
+  MagicNumber:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    ignoreNumbers: ['-1', '0', '1', '2']
+    ignoreHashCodeFunction: true
+    ignorePropertyDeclaration: false
+    ignoreLocalVariableDeclaration: false
+    ignoreConstantDeclaration: true
+    ignoreCompanionObjectPropertyDeclaration: true
+    ignoreAnnotation: false
+    ignoreNamedArgument: true
+    ignoreEnums: false
+    ignoreRanges: false
+  MandatoryBracesIfStatements:
+    active: false
+  MandatoryBracesLoops:
+    active: false
+  MaxLineLength:
+    active: true
+    maxLineLength: 120
+    excludePackageStatements: true
+    excludeImportStatements: true
+    excludeCommentStatements: false
+  MayBeConst:
+    active: true
+  ModifierOrder:
+    active: true
+  NestedClassesVisibility:
+    active: false
+  NewLineAtEndOfFile:
+    active: true
+  NoTabs:
+    active: false
+  OptionalAbstractKeyword:
+    active: true
+  OptionalUnit:
+    active: false
+  OptionalWhenBraces:
+    active: false
+  PreferToOverPairSyntax:
+    active: false
+  ProtectedMemberInFinalClass:
+    active: true
+  RedundantExplicitType:
+    active: false
+  RedundantVisibilityModifierRule:
+    active: false
+  ReturnCount:
+    active: true
+    max: 2
+    excludedFunctions: 'equals'
+    excludeLabeled: false
+    excludeReturnFromLambda: true
+    excludeGuardClauses: false
+  SafeCast:
+    active: true
+  SerialVersionUIDInSerializableClass:
+    active: false
+  SpacingBetweenPackageAndImports:
+    active: false
+  ThrowsCount:
+    active: true
+    max: 2
+  TrailingWhitespace:
+    active: false
+  UnderscoresInNumericLiterals:
+    active: false
+    acceptableDecimalLength: 5
+  UnnecessaryAbstractClass:
+    active: true
+    excludeAnnotatedClasses: ['dagger.Module']
+  UnnecessaryAnnotationUseSiteTarget:
+    active: false
+  UnnecessaryApply:
+    active: false
+  UnnecessaryInheritance:
+    active: true
+  UnnecessaryLet:
+    active: false
+  UnnecessaryParentheses:
+    active: false
+  UntilInsteadOfRangeTo:
+    active: false
+  UnusedImports:
+    active: false
+  UnusedPrivateClass:
+    active: true
+  UnusedPrivateMember:
+    active: false
+    allowedNames: '(_|ignored|expected|serialVersionUID)'
+  UseArrayLiteralsInAnnotations:
+    active: false
+  UseCheckNotNull:
+    active: false
+  UseCheckOrError:
+    active: false
+  UseDataClass:
+    active: false
+    excludeAnnotatedClasses: []
+    allowVars: false
+  UseEmptyCounterpart:
+    active: false
+  UseIfInsteadOfWhen:
+    active: false
+  UseRequire:
+    active: false
+  UseRequireNotNull:
+    active: false
+  UselessCallOnNotNull:
+    active: true
+  UtilityClassWithPublicConstructor:
+    active: true
+  VarCouldBeVal:
+    active: false
+  WildcardImport:
+    active: true
+    excludes: ['**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**']
+    excludeImports: ['java.util.*', 'kotlinx.android.synthetic.*']
diff --git a/src/main/kotlin/staks/CompoundHandler.kt b/src/main/kotlin/staks/CompoundHandler.kt
index e128807..c69356c 100644
--- a/src/main/kotlin/staks/CompoundHandler.kt
+++ b/src/main/kotlin/staks/CompoundHandler.kt
@@ -2,20 +2,24 @@ package staks
 
 import javax.xml.stream.XMLEventReader
 
+/**
+ * Basic class which describes handler, which is built from another handlers.
+ */
 abstract class CompoundHandler<T> : Handler<T> {
     /**
-     * Child handlers of current compound handler
+     * Child handlers of current compound handler.
      */
     val children = hashSetOf<Handler<*>>()
 
     /**
-     * every CompoundHandler should have access to XMLEventReader because it will potentially pass it to child for handling
-     * Added for extensibility
+     * every CompoundHandler should have access to XMLEventReader because it will potentially pass it to child
+     * for handling.
+     * Added for extensibility.
      */
     abstract val reader: XMLEventReader
 
     /**
-     * Every child should be registered for us to be able to pass handling to it if it should be done
+     * Every child should be registered for us to be able to pass handling to it if it should be done.
      */
     fun <R : Handler<*>> registerChild(child: R): R {
         children.add(child)
@@ -23,8 +27,9 @@ abstract class CompoundHandler<T> : Handler<T> {
     }
 
     /**
-     * Sometimes we need to wrap one delegate with another — for example if underlying delegate's data should be transformed somehow.
-     * It should be achieved with decorate call
+     * Sometimes we need to wrap one delegate with another — for example if underlying delegate's data
+     * should be transformed somehow.
+     * It should be achieved with decorate call.
      */
     fun <DECORATOR : ContainerHandler<*, *>> decorate(child: DECORATOR): DECORATOR {
         children.remove(child.child)
@@ -33,12 +38,13 @@ abstract class CompoundHandler<T> : Handler<T> {
     }
 
     /**
-     * Marks handler as optional. By default if result is `null` exception will be thrown. Optional handler will return null
+     * Marks handler as optional. By default if result is `null` exception will be thrown. Optional handler will
+     * return null.
      */
     fun <Z : Any> Handler<Z>.optional() = decorate(OptionalHandler(this))
 
     /**
-     * Converts underlying handler's result to int or throws Exception
+     * Converts underlying handler's result to int or throws Exception.
      */
     fun Handler<String>.int() = decorate(IntHandler(this))
 
diff --git a/src/main/kotlin/staks/Handler.kt b/src/main/kotlin/staks/Handler.kt
index 7588924..5f43a83 100644
--- a/src/main/kotlin/staks/Handler.kt
+++ b/src/main/kotlin/staks/Handler.kt
@@ -2,39 +2,43 @@ package staks
 
 import javax.xml.stream.events.XMLEvent
 
+/**
+ * Basic interface for everything that should handle [XMLEvent]s.
+ */
 interface Handler<T> {
     /**
-     * Producer of value which was parser from XML
+     * Producer of value which was parser from XML.
      */
     val value: () -> T
 
     /**
-     * true if should not be matched after first match
+     * true if should not be matched after first match.
      */
     val isSingular: Boolean
 
     /**
-     * true if this concrete handler cares about these concrete event
+     * true if this concrete handler cares about these concrete event.
      */
     fun matches(event: XMLEvent): Boolean
 
     /**
-     * Handle the XMLEvent and fill the result if needed
-     * It's responsibility of handler to leave XMLEventReader in consistent state — for example wait for corresponding closing tag
+     * Handle the XMLEvent and fill the result if needed.
+     * It's responsibility of handler to leave XMLEventReader in consistent state — for example wait for
+     * corresponding closing tag.
      * @throws IllegalArgumentException if can not build object
      */
     fun process(ev: XMLEvent)
 
     /**
      * Clear the state: Most probably the handler is stateful, but it may be invoked several times if, for example,
-     * it' inside list — the same handler will be invoked on every list invocation
+     * it' inside list — the same handler will be invoked on every list invocation.
      */
     fun reset()
 
     /**
-     * call handler to obtain earlier calculated value
+     * call handler to obtain earlier calculated value.
      * @throws IllegalArgumentException if can not parse data ot ir's not available
      * @return T
      */
     operator fun invoke() = value.invoke()
-}
\ No newline at end of file
+}
diff --git a/src/main/kotlin/staks/ListHandler.kt b/src/main/kotlin/staks/ListHandler.kt
index 611cc9a..b2b0c3a 100644
--- a/src/main/kotlin/staks/ListHandler.kt
+++ b/src/main/kotlin/staks/ListHandler.kt
@@ -3,6 +3,9 @@ package staks
 import javax.xml.stream.XMLEventReader
 import javax.xml.stream.events.XMLEvent
 
+/**
+ * Handler which returns list of [T] or throws [IllegalArgumentException] if resulting list is empty.
+ */
 class ListHandler<T>(
     private val tagName: String,
     func: CompoundHandler<*>.() -> () -> T,
@@ -32,7 +35,7 @@ class ListHandler<T>(
                 try {
                     result.add(builder())
                     return
-                } catch (e: Exception) {
+                } catch (e: IllegalArgumentException) {
                     throw IllegalArgumentException("Unable to build info from $tagName", e)
                 }
             }
@@ -47,4 +50,4 @@ class ListHandler<T>(
     override fun reset() {
         result = ArrayList()
     }
-}
\ No newline at end of file
+}
diff --git a/src/main/kotlin/staks/SingleHandler.kt b/src/main/kotlin/staks/SingleHandler.kt
index da17ed6..13dba97 100644
--- a/src/main/kotlin/staks/SingleHandler.kt
+++ b/src/main/kotlin/staks/SingleHandler.kt
@@ -3,6 +3,9 @@ package staks
 import javax.xml.stream.XMLEventReader
 import javax.xml.stream.events.XMLEvent
 
+/**
+ * Handler, which returns first instance of type [T] ot throws exception if it wasn't found.
+ */
 class SingleHandler<T : Any>(
     private val tagName: String,
     override val reader: XMLEventReader,
@@ -11,7 +14,7 @@ class SingleHandler<T : Any>(
     CompoundHandler<T>() {
     private var result: T? = null
 
-    val builder = func()
+    private val builder = func()
 
     override val value: () -> T
         get() = {
@@ -44,4 +47,4 @@ class SingleHandler<T : Any>(
     override fun reset() {
         result = null
     }
-}
\ No newline at end of file
+}
diff --git a/src/main/kotlin/staks/UnnamedListHandler.kt b/src/main/kotlin/staks/UnnamedListHandler.kt
index 3ba5b96..0b832f7 100644
--- a/src/main/kotlin/staks/UnnamedListHandler.kt
+++ b/src/main/kotlin/staks/UnnamedListHandler.kt
@@ -2,6 +2,9 @@ package staks
 
 import javax.xml.stream.events.XMLEvent
 
+/**
+ * Handler which returns all instances of underlying child Handler.
+ */
 class UnnamedListHandler<T>(override val child: Handler<T>) : ContainerHandler<T, List<T>> {
     private var result = arrayListOf<T>()
 
diff --git a/src/main/kotlin/staks/base.kt b/src/main/kotlin/staks/base.kt
index d54578d..c086679 100644
--- a/src/main/kotlin/staks/base.kt
+++ b/src/main/kotlin/staks/base.kt
@@ -11,30 +11,133 @@ import javax.xml.stream.events.XMLEvent
 import javax.xml.transform.Source
 import javax.xml.stream.XMLStreamReader as XMLSR
 
+/**
+ * Main entry point for building objects.
+ * Usage example:
+ * ```kotlin
+ * val text = staks(inputStream){
+ *     val txt = tagText("a");
+ *     { txt() }
+ * }
+ * ```
+ * Here `text` will contain content of first met `a` tag in XML document. Parsing is lazy, so it will stop after
+ * first found `a` tag.
+ * @return [T]
+ */
 fun <T> staks(input: InputStream, func: (StaxBuilder<T>.() -> () -> T)) = StaxBuilder(reader(input), func).process()
+/**
+ * Main entry point for building objects.
+ * Usage example:
+ * ```kotlin
+ * val text = staks(inputStream, encoding){
+ *     val txt = tagText("a");
+ *     { txt() }
+ * }
+ * ```
+ * Here `text` will contain content of first met `a` tag in XML document. Parsing is lazy, so it will stop after
+ * first found `a` tag.
+ * @return [T]
+ */
 fun <T> staks(input: InputStream, encoding: String, func: (StaxBuilder<T>.() -> () -> T)) =
     StaxBuilder(reader(input, encoding), func).process()
 
+/**
+ * Main entry point for building objects.
+ * Usage example:
+ * ```kotlin
+ * val text = staks(file){
+ *     val txt = tagText("a");
+ *     { txt() }
+ * }
+ * ```
+ * Here `text` will contain content of first met `a` tag in XML document. Parsing is lazy, so it will stop after
+ * first found `a` tag.
+ * @return [T]
+ */
 fun <T> staks(file: File, func: (StaxBuilder<T>.() -> () -> T)) = StaxBuilder(reader(file), func).process()
+/**
+ * Main entry point for building objects.
+ * Usage example:
+ * ```kotlin
+ * val text = staks(source){
+ *     val txt = tagText("a");
+ *     { txt() }
+ * }
+ * ```
+ * Here `text` will contain content of first met `a` tag in XML document. Parsing is lazy, so it will stop after
+ * first found `a` tag.
+ * @param source [Source]
+ * @return [T]
+ */
+
 fun <T> staks(source: Source, func: (StaxBuilder<T>.() -> () -> T)) = StaxBuilder(reader(source), func).process()
+/**
+ * Main entry point for building objects.
+ * Usage example:
+ * ```kotlin
+ * val text = staks(xmlStreamReader){
+ *     val txt = tagText("a");
+ *     { txt() }
+ * }
+ * ```
+ * Here `text` will contain content of first met `a` tag in XML document. Parsing is lazy, so it will stop after
+ * first found `a` tag.
+ * @return [T]
+ */
 fun <T> staks(reader: XMLSR, func: (StaxBuilder<T>.() -> () -> T)) = StaxBuilder(reader(reader), func).process()
+/**
+ * Main entry point for building objects.
+ * Usage example:
+ * ```kotlin
+ * val text = staks(url){
+ *     val txt = tagText("a");
+ *     { txt() }
+ * }
+ * ```
+ * Here `text` will contain content of first met `a` tag in XML document. Parsing is lazy, so it will stop after
+ * first found `a` tag.
+ * @return [T]
+ */
 fun <T> staks(src: URL, func: (StaxBuilder<T>.() -> () -> T)) = StaxBuilder(reader(src), func).process()
 
+/**
+ * Provider user with [XMLEventReader], suitable for usage with [StaxBuilder].
+ */
 fun reader(file: File) = factory().createXMLEventReader(file)
+
+/**
+ * Provider user with [XMLEventReader], suitable for usage with [StaxBuilder].
+ */
 fun reader(inputStream: InputStream) = factory().createXMLEventReader(inputStream)
+/**
+ * Provider user with [XMLEventReader], suitable for usage with [StaxBuilder].
+ */
 fun reader(inputStream: InputStream, encoding: String) = factory().createXMLEventReader(inputStream, encoding)
+/**
+ * Provider user with [XMLEventReader], suitable for usage with [StaxBuilder].
+ */
 fun reader(reader: XMLSR) = factory().createXMLEventReader(reader)
+/**
+ * Provider user with [XMLEventReader], suitable for usage with [StaxBuilder].
+ */
 fun reader(source: Source) = factory().createXMLEventReader(source)
+/**
+ * Provider user with [XMLEventReader], suitable for usage with [StaxBuilder].
+ */
 fun reader(source: URL) = factory().createXMLEventReader(source)
 
 private fun factory(): XMLInputFactory2 =
     (XMLInputFactory2.newInstance() as XMLInputFactory2).also { it.configureForConvenience() }
 
+/**
+ * Root [CompoundHandler] which creates reader and passes [XMLEvent] to underlying registered handlers and evetually
+ * returns built entity via calling `process method`. For usage examples @see [staks].
+ */
 class StaxBuilder<T>(override val reader: XMLEventReader, func: StaxBuilder<T>.() -> () -> T) : CompoundHandler<T>() {
 
-    val builder = func()
+    private val builder = func()
 
-    fun process(): T {
+    internal fun process(): T {
         while (reader.hasNext()) {
             val ev = reader.nextEvent()
             for (it in children.filter { it.matches(ev) }) {
@@ -58,13 +161,13 @@ class StaxBuilder<T>(override val reader: XMLEventReader, func: StaxBuilder<T>.(
 }
 
 /**
- * Extracts data from tag assuming it contains only text or the first text met inside tag
+ * Extracts data from tag assuming it contains only text or the first text met inside tag.
  */
 fun CompoundHandler<*>.tagText(tagName: String): TagTextHandler =
     registerChild(TagTextHandler(tagName, reader))
 
 /**
- * Extracts data from tag's attribute
+ * Extracts data from tag's attribute.
  */
 fun CompoundHandler<*>.attribute(tagName: String, attributeName: String): AttrHandler =
     registerChild(AttrHandler(tagName, attributeName))
@@ -79,13 +182,17 @@ fun CompoundHandler<*>.attribute(tagName: String, attributeName: String): AttrHa
  *   { data() }
  * }
  * ```
- * After parsing `names()` will contain list of contants of `inner-tag-name` tags
+ * After parsing `names()` will contain list of contants of `inner-tag-name` tags.
  * @param tagName name of outer tag
  * @param func description of inner tags
  */
 fun <T> CompoundHandler<*>.list(tagName: String, func: CompoundHandler<*>.() -> () -> T) =
     registerChild(ListHandler(tagName, func, reader))
 
+/**
+ * Creates [UnnamedListHandler] from supplied handler.
+ * @param handler — underlying Handler with `isSingular` true. Behavior for `isSinguar` false is not defined.
+ */
 fun <T> CompoundHandler<*>.list(handler: Handler<T>): Handler<List<T>> = decorate(UnnamedListHandler(handler))
 
 /**
@@ -107,4 +214,3 @@ fun <T> CompoundHandler<*>.list(handler: Handler<T>): Handler<List<T>> = decorat
  */
 fun <T : Any> CompoundHandler<*>.single(tagName: String, func: CompoundHandler<*>.() -> () -> T): SingleHandler<T> =
     registerChild(SingleHandler(tagName, reader, func))
-
diff --git a/src/main/kotlin/staks/delegates.kt b/src/main/kotlin/staks/delegates.kt
index e4dd321..558a767 100644
--- a/src/main/kotlin/staks/delegates.kt
+++ b/src/main/kotlin/staks/delegates.kt
@@ -3,7 +3,9 @@ package staks
 import javax.xml.stream.XMLEventReader
 import javax.xml.stream.events.XMLEvent
 
-
+/**
+ * Handler which converts underlying handler's String value to Int or throws [IllegalArgumentException].
+ */
 class IntHandler(override val child: Handler<String>) : DecoratingHandler<Int, String> {
     override val value: () -> Int
         get() = {
@@ -14,6 +16,11 @@ class IntHandler(override val child: Handler<String>) : DecoratingHandler<Int, S
     override fun reset() = child.reset()
 }
 
+/**
+ * Handler which extracts first met text inside tag with tagName param.
+ * @param tagName name of tag inside which text should be searched for.
+ * @throws [IllegalArgumentException] if text is not found.
+ */
 class TagTextHandler(
     private val tagName: String,
     private val reader: XMLEventReader
@@ -43,13 +50,18 @@ class TagTextHandler(
     override val isSingular: Boolean = true
 }
 
-
+/**
+ * Handler, returning value of specified attribute.
+ */
 class AttrHandler(private val tagName: String, private val attributeName: String) : Handler<String> {
     private var result: String? = null
     override val value: () -> String
         get() {
             return {
-                require(result != null) { "Unable to extract text from $tagName with attribute $attributeName, maybe it should be declared optional()" }
+                require(result != null) {
+                    "Unable to extract text from $tagName with attribute $attributeName, " +
+                            "maybe it should be declared optional()"
+                }
                 result!!
             }
         }
@@ -70,23 +82,38 @@ class AttrHandler(private val tagName: String, private val attributeName: String
     }
 }
 
-interface ContainerHandler<T, R>:Handler<R>{
+/**
+ * Basic [Handler] interface, which contains exactly on child Handler. Made for replacing one handler's result
+ * which another.
+ */
+interface ContainerHandler<T, R> : Handler<R> {
+    /**
+     * Child handler.
+     */
     val child: Handler<T>
 }
 
+/**
+ * [ContainerHandler] implementaion, which passes everything necessary tto underlying [Handler], but explicitly knows
+ * that it may return another type.
+ */
 interface DecoratingHandler<RESULT, SOURCE> : Handler<RESULT>, ContainerHandler<SOURCE, RESULT> {
     override val child: Handler<SOURCE>
     override val isSingular: Boolean get() = child.isSingular
     override fun matches(event: XMLEvent): Boolean = child.matches(event)
 }
 
+/**
+ * [DecoratingHandler] which will swallow exption while getting result from child handler and will return `null`
+ * instead.
+ */
 class OptionalHandler<Z : Any>(override val child: Handler<Z>) : DecoratingHandler<Z?, Z> {
     override val value: () -> Z?
         get() {
             return {
                 try {
                     child.value()
-                } catch (e: Exception) {
+                } catch (_: Exception) {
                     null
                 }
             }
diff --git a/src/test/kotlin/staks/BaseKtTest.kt b/src/test/kotlin/staks/BaseKtTest.kt
index 230a571..6cca188 100644
--- a/src/test/kotlin/staks/BaseKtTest.kt
+++ b/src/test/kotlin/staks/BaseKtTest.kt
@@ -7,7 +7,8 @@ import io.kotest.core.spec.style.FunSpec
 class BaseKtTest : FunSpec({
     test("should parse basic xml") {
         val input =
-            """<note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body> </note>""".byteInputStream()
+            ("<note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading>" +
+                    "<body>Don't forget me this weekend!</body></note>").byteInputStream()
 
         data class Note(
             val to: String,
@@ -59,7 +60,8 @@ class BaseKtTest : FunSpec({
     }
     test("should parse list of attributes") {
         val input =
-            "<root><data attr='text' attr2='text2'>inside2</data><data attr='text3' attr2='text4'>inside2</data></root>".byteInputStream()
+            ("<root><data attr='text' attr2='text2'>inside2</data><data attr='text3' attr2='text4'>inside2</data>" +
+                    "</root>").byteInputStream()
         val attr = staks<List<String>>(input) {
             val lst = list(attribute("data", "attr"));
             { lst() }
@@ -82,9 +84,9 @@ class BaseKtTest : FunSpec({
 
     }
     test("compound list should produce list of compound objects") {
-        //language=XML
         val inp =
-            "<root><el><a>a1</a><b>b1</b><c>c1</c></el><el><a>a2</a><b>b2</b><c>c2</c></el><el><a>a3</a><b>b3</b><c>c3</c></el></root>".byteInputStream()
+            ("<root><el><a>a1</a><b>b1</b><c>c1</c></el><el><a>a2</a><b>b2</b><c>c2</c></el><el><a>a3</a><b>b3</b>" +
+                    "<c>c3</c></el></root>").byteInputStream()
         val lst = staks<List<Triple<String, String, String>>>(inp) {
             val lst = list("el") {
                 val a = tagText("a")
@@ -113,7 +115,8 @@ class BaseKtTest : FunSpec({
         )
     }
     test("optional should return null of object is not found") {
-        val inp = "<root><el><a>a1</a><b>b1</b><d>c1</d></el><el><a>a2</a><b>b2</b><c>c2</c></el><el><a>a3</a><b>b3</b><c>c3</c></el></root>".byteInputStream()
+        val inp = ("<root><el><a>a1</a><b>b1</b><d>c1</d></el><el><a>a2</a><b>b2</b><c>c2</c></el><el><a>a3</a>" +
+                "<b>b3</b><c>c3</c></el></root>").byteInputStream()
         val lst = staks<List<String?>>(inp) {
             val lst = list("el") {
                 val c = tagText("d").optional();
@@ -125,7 +128,8 @@ class BaseKtTest : FunSpec({
 
     }
     test("int should return int if can convert") {
-        val inp = "<root><el><a>a1</a><b>b1</b><c>1</c></el><el><a>a2</a><b>b2</b><c>2</c></el><el><a>a3</a><b>b3</b><c>3</c></el></root>".byteInputStream()
+        val inp = ("<root><el><a>a1</a><b>b1</b><c>1</c></el><el><a>a2</a><b>b2</b><c>2</c></el><el><a>a3</a>" +
+                "<b>b3</b><c>3</c></el></root>").byteInputStream()
         val lst = staks<List<Int>>(inp) {
             val lst = list("el") {
                 val c = tagText("c").int();
@@ -137,7 +141,8 @@ class BaseKtTest : FunSpec({
 
     }
     test("error while building list should fail build of list") {
-        val inp = "<root><el><a>a1</a><b>b1</b><c>a</c></el><el><a>a2</a><b>b2</b><c>2</c></el><el><a>a3</a><b>b3</b><c>3</c></el></root>".byteInputStream()
+        val inp = ("<root><el><a>a1</a><b>b1</b><c>a</c></el><el><a>a2</a><b>b2</b><c>2</c></el>" +
+                "<el><a>a3</a><b>b3</b><c>3</c></el></root>").byteInputStream()
         expect {
             staks<List<Int>>(inp) {
                 val lst = list("el") {
@@ -150,9 +155,9 @@ class BaseKtTest : FunSpec({
     }
 
     test("compoud list of simple lists") {
-        //language=XML
         val input =
-            "<root><el><a>x1</a><a>x2</a></el><el><a>x3</a><a>x4</a></el><el><a>x5</a><a>x6</a></el></root>".byteInputStream()
+            ("<root><el><a>x1</a><a>x2</a></el><el><a>x3</a><a>x4</a></el><el><a>x5</a><a>x6</a></el></root>")
+                .byteInputStream()
         val list = staks<List<List<String>>>(input) {
             val higher = list("el") {
                 val inner = list(tagText("a"));
@@ -163,7 +168,6 @@ class BaseKtTest : FunSpec({
         expect(list.flatten()) contains o inGiven order and only the values("x1", "x2", "x3", "x4", "x5", "x6")
     }
     test("tag text returns only first value") {
-        //language=XML
         val input = "<root><a>test1</a><a>test2</a></root>".byteInputStream()
         val tst = staks<String>(input) {
             val txt = tagText("a");
@@ -172,9 +176,32 @@ class BaseKtTest : FunSpec({
         expect(tst) toBe "test1"
     }
     test("list inside singe inside list") {
-        //language=XML
-        val input =
-            "<root><list-one><single><list-two><a>a1</a><b>b1</b></list-two><list-two><a>a2</a><b>b2</b></list-two></single></list-one><list-one><single><list-two><a>a3</a><b>b3</b></list-two><list-two><a>a4</a><b>b4</b></list-two></single></list-one></root>".byteInputStream()
+        val input = """<root>
+    <list-one>
+        <single>
+            <list-two>
+                <a>a1</a>
+                <b>b1</b>
+            </list-two>
+            <list-two>
+                <a>a2</a>
+                <b>b2</b>
+            </list-two>
+        </single>
+    </list-one>
+    <list-one>
+        <single>
+            <list-two>
+                <a>a3</a>
+                <b>b3</b>
+            </list-two>
+            <list-two>
+                <a>a4</a>
+                <b>b4</b>
+            </list-two>
+        </single>
+    </list-one>
+</root>""".byteInputStream()
         val d = staks<List<List<Pair<String, String>>>>(input) {
             val lSLP = list("list-one") {
                 val sLP = single("single") {
@@ -197,7 +224,6 @@ class BaseKtTest : FunSpec({
         )
     }
     test("single wil be read only once") {
-        //language=XML
         val input =
             "<root><single><a>a1</a><b>b1</b></single><single><a>a2</a><b>b2</b></single></root>".byteInputStream()
         val d = staks<Pair<String, String>>(input) {
@@ -214,4 +240,4 @@ class BaseKtTest : FunSpec({
         expect(d) toBe ("a1" to "b1")
     }
 
-})
\ No newline at end of file
+})