diff --git a/src/codergpt/explainer/__init__.py b/src/codergpt/explainer/__init__.py
index 894a12b..801b894 100644
--- a/src/codergpt/explainer/__init__.py
+++ b/src/codergpt/explainer/__init__.py
@@ -1 +1,5 @@
 """Code explanation module."""
+
+from .explainer import CodeExplainer
+
+__all__ = ["CodeExplainer", "ExpressionEvaluator"]
diff --git a/src/codergpt/explainer/explainer.py b/src/codergpt/explainer/explainer.py
index 1b11ce4..b75b39c 100644
--- a/src/codergpt/explainer/explainer.py
+++ b/src/codergpt/explainer/explainer.py
@@ -6,52 +6,7 @@
 
 from langchain_core.runnables.base import RunnableSerializable
 
-
-class ExpressionEvaluator(ast.NodeVisitor):
-    """Evaluate the code expression and extract the source code of the specified function or class."""
-
-    def __init__(self, source_code, function_name=None, class_name=None):
-        """
-        Initialize the ExpressionEvaluator class.
-
-        :param function_name: The name of the function to find in the source code.
-        :type function_name: str or None
-        :param class_name: The name of the class to find in the source code.
-        :type class_name: str or None
-        """
-        self.function_code = None
-        self.class_code = None
-        self.function_name = function_name
-        self.class_name = class_name
-        self.source_code = source_code
-
-    def visit_FunctionDef(self, node):
-        """
-        Visit a FunctionDef (function definition) node in the AST.
-
-        If the function name matches the target function name, it extracts the source segment.
-
-        :param node: The node representing a function definition in the AST.
-        :type node: ast.FunctionDef
-        """
-        if self.function_name == node.name:
-            self.function_code = ast.get_source_segment(self.source_code, node)
-        # Continue the traversal in case there are nested functions or classes
-        self.generic_visit(node)
-
-    def visit_ClassDef(self, node):
-        """
-        Visit a ClassDef (class definition) node in the AST.
-
-        If the class name matches the target class name, it extracts the source segment.
-
-        :param node: The node representing a class definition in the AST.
-        :type node: ast.ClassDef
-        """
-        if self.class_name == node.name:
-            self.class_code = ast.get_source_segment(self.source_code, node)
-        # Continue the traversal in case there are nested functions or classes
-        self.generic_visit(node)
+from codergpt.utils.expression_evaluator import ExpressionEvaluator
 
 
 class CodeExplainer:
diff --git a/src/codergpt/utils/expression_evaluator.py b/src/codergpt/utils/expression_evaluator.py
new file mode 100644
index 0000000..2db172c
--- /dev/null
+++ b/src/codergpt/utils/expression_evaluator.py
@@ -0,0 +1,54 @@
+"""
+The ExpressionEvaluator Class.
+
+Used for evaluating the code expression and extracting the source code of the specified function or class.
+"""
+
+import ast
+
+
+class ExpressionEvaluator(ast.NodeVisitor):
+    """Evaluate the code expression and extract the source code of the specified function or class."""
+
+    def __init__(self, source_code, function_name=None, class_name=None):
+        """
+        Initialize the ExpressionEvaluator class.
+
+        :param function_name: The name of the function to find in the source code.
+        :type function_name: str or None
+        :param class_name: The name of the class to find in the source code.
+        :type class_name: str or None
+        """
+        self.function_code = None
+        self.class_code = None
+        self.function_name = function_name
+        self.class_name = class_name
+        self.source_code = source_code
+
+    def visit_FunctionDef(self, node):
+        """
+        Visit a FunctionDef (function definition) node in the AST.
+
+        If the function name matches the target function name, it extracts the source segment.
+
+        :param node: The node representing a function definition in the AST.
+        :type node: ast.FunctionDef
+        """
+        if self.function_name == node.name:
+            self.function_code = ast.get_source_segment(self.source_code, node)
+        # Continue the traversal in case there are nested functions or classes
+        self.generic_visit(node)
+
+    def visit_ClassDef(self, node):
+        """
+        Visit a ClassDef (class definition) node in the AST.
+
+        If the class name matches the target class name, it extracts the source segment.
+
+        :param node: The node representing a class definition in the AST.
+        :type node: ast.ClassDef
+        """
+        if self.class_name == node.name:
+            self.class_code = ast.get_source_segment(self.source_code, node)
+        # Continue the traversal in case there are nested functions or classes
+        self.generic_visit(node)