diff --git a/staff/manuel-barzi/playground/arrays/Array.prototype.indexOf.js b/staff/manuel-barzi/playground/arrays/Array.prototype.indexOf.js
new file mode 100644
index 00000000..23a6d1a1
--- /dev/null
+++ b/staff/manuel-barzi/playground/arrays/Array.prototype.indexOf.js
@@ -0,0 +1,17 @@
+console.log('TEST Array.prototype.indexOf')
+
+console.log('CASE get index of c')
+
+var chars = ['a', 'b', 'c', 'b', 'a']
+
+var index = chars.indexOf('c')
+console.log(index)
+// 2
+
+console.log('CASE get index of c from index -2')
+
+var chars = ['a', 'b', 'c', 'b', 'a']
+
+var index = chars.indexOf('c', -2)
+console.log(index)
+// -1
\ No newline at end of file
diff --git a/staff/manuel-barzi/playground/arrays/Array.prototype.push.js b/staff/manuel-barzi/playground/arrays/Array.prototype.push.js
index 9c0afcab..d22e8559 100644
--- a/staff/manuel-barzi/playground/arrays/Array.prototype.push.js
+++ b/staff/manuel-barzi/playground/arrays/Array.prototype.push.js
@@ -18,4 +18,14 @@ var length = fruits.push('banana')
 console.log(fruits)
 // ['apple', 'orange', 'raspberry', 'pineapple', 'banana'] (5)
 console.log(length)
-// 5
\ No newline at end of file
+// 5
+
+console.log('CASE add banana pear and coconut to fruits')
+
+var fruits = ['apple', 'orange', 'raspberry', 'pineapple']
+var length = fruits.push('banana', 'pear', 'coconut')
+
+console.log(fruits)
+// ['apple', 'orange', 'raspberry', 'pineapple', 'banana', 'pear', 'coconut'] (7)
+console.log(length)
+// 7
\ No newline at end of file
diff --git a/staff/manuel-barzi/playground/iterables/indexOf.1.js b/staff/manuel-barzi/playground/iterables/indexOf.1.js
new file mode 100644
index 00000000..634dddbb
--- /dev/null
+++ b/staff/manuel-barzi/playground/iterables/indexOf.1.js
@@ -0,0 +1,25 @@
+var indexOf = function (iterable, searchElement) {
+    /*
+    iterate on iterable
+    if searchElement found then return index
+    otherwise return -1
+    */
+
+    for (var i = 0; i < iterable.length; i++) {
+        var element = iterable[i]
+
+        if (element === searchElement) return i
+    }
+
+    return -1
+}
+
+console.log('TEST indexOf')
+
+console.log('CASE get index of c')
+
+var chars = { 0: 'a', 1: 'b', 2: 'c', 3: 'b', 4: 'a', length: 5 }
+
+var index = indexOf(chars, 'c')
+console.log(index)
+// 2
\ No newline at end of file
diff --git a/staff/manuel-barzi/playground/iterables/indexOf.2.js b/staff/manuel-barzi/playground/iterables/indexOf.2.js
new file mode 100644
index 00000000..e5caa654
--- /dev/null
+++ b/staff/manuel-barzi/playground/iterables/indexOf.2.js
@@ -0,0 +1,43 @@
+var indexOf = function (iterable, searchElement, fromIndex) {
+    /*
+    iterate on iterable
+    if searchElement found then return index
+    otherwise return -1
+    */
+
+    /*
+    iterate on iterable from index fromIndex
+    if searchElement found then return index
+    otherwise return -1
+    */
+
+    for (
+        var i = (fromIndex === undefined ? 0 : (fromIndex >= 0 ? fromIndex : fromIndex + iterable.length));
+        i < iterable.length;
+        i++
+    ) {
+        var element = iterable[i]
+
+        if (element === searchElement) return i
+    }
+
+    return -1
+}
+
+console.log('TEST indexOf')
+
+console.log('CASE get index of c')
+
+var chars = { 0: 'a', 1: 'b', 2: 'c', 3: 'b', 4: 'a', length: 5 }
+
+var index = indexOf(chars, 'c')
+console.log(index)
+// 2
+
+console.log('CASE get index of c from index -2')
+
+var chars = { 0: 'a', 1: 'b', 2: 'c', 3: 'b', 4: 'a', length: 5 }
+
+var index = indexOf(chars, 'c', -2)
+console.log(index)
+// -1
\ No newline at end of file
diff --git a/staff/manuel-barzi/playground/iterables/indexOf.js b/staff/manuel-barzi/playground/iterables/indexOf.js
new file mode 100644
index 00000000..9bb87896
--- /dev/null
+++ b/staff/manuel-barzi/playground/iterables/indexOf.js
@@ -0,0 +1,43 @@
+var indexOf = function (iterable, searchElement, fromIndex) {
+    /*
+    iterate on iterable
+    if searchElement found then return index
+    otherwise return -1
+    */
+
+    /*
+    iterate on iterable from index fromIndex
+    if searchElement found then return index
+    otherwise return -1
+    */
+
+    for (
+        var i = (arguments.length === 2 ? 0 : (fromIndex >= 0 ? fromIndex : fromIndex + iterable.length));
+        i < iterable.length;
+        i++
+    ) {
+        var element = iterable[i]
+
+        if (element === searchElement) return i
+    }
+
+    return -1
+}
+
+console.log('TEST indexOf')
+
+console.log('CASE get index of c')
+
+var chars = { 0: 'a', 1: 'b', 2: 'c', 3: 'b', 4: 'a', length: 5 }
+
+var index = indexOf(chars, 'c')
+console.log(index)
+// 2
+
+console.log('CASE get index of c from index -2')
+
+var chars = { 0: 'a', 1: 'b', 2: 'c', 3: 'b', 4: 'a', length: 5 }
+
+var index = indexOf(chars, 'c', -2)
+console.log(index)
+// -1
\ No newline at end of file
diff --git a/staff/manuel-barzi/playground/iterables/push.1.js b/staff/manuel-barzi/playground/iterables/push.1.js
new file mode 100644
index 00000000..e18cfc44
--- /dev/null
+++ b/staff/manuel-barzi/playground/iterables/push.1.js
@@ -0,0 +1,28 @@
+var push = function (iterable, element) {
+    iterable[iterable.length] = element
+    iterable.length++
+
+    return iterable.length
+}
+
+console.log('TEST push')
+
+console.log('CASE add 400 to nums')
+
+var nums = { 0: 100, 1: 200, 2: 300, length: 3 }
+var length = push(nums, 400)
+
+console.log(nums)
+// { 0: 100, 1: 200, 2: 300, 3: 400, length: 4 }
+console.log(length)
+// 4
+
+console.log('CASE add banana to fruits')
+
+var fruits = { 0: 'apple', 1: 'orange', 2: 'raspberry', 3: 'pineapple', length: 4 }
+var length = push(fruits, 'banana')
+
+console.log(fruits)
+// { 0: 'apple', 1: 'orange', 2: 'raspberry', 3: 'pineapple', 4: 'banana', length: 5 }
+console.log(length)
+// 5
\ No newline at end of file
diff --git a/staff/manuel-barzi/playground/iterables/push.js b/staff/manuel-barzi/playground/iterables/push.js
index e18cfc44..f3f88cb9 100644
--- a/staff/manuel-barzi/playground/iterables/push.js
+++ b/staff/manuel-barzi/playground/iterables/push.js
@@ -1,6 +1,15 @@
 var push = function (iterable, element) {
-    iterable[iterable.length] = element
-    iterable.length++
+    if (arguments.length === 2) {
+        iterable[iterable.length] = element
+        iterable.length++
+    } else {
+        for (var i = 1; i < arguments.length; i++) {
+            var element = arguments[i]
+
+            iterable[iterable.length] = element
+            iterable.length++
+        }
+    }
 
     return iterable.length
 }
@@ -25,4 +34,14 @@ var length = push(fruits, 'banana')
 console.log(fruits)
 // { 0: 'apple', 1: 'orange', 2: 'raspberry', 3: 'pineapple', 4: 'banana', length: 5 }
 console.log(length)
-// 5
\ No newline at end of file
+// 5
+
+console.log('CASE add banana pear and coconut to fruits')
+
+var fruits = { 0: 'apple', 1: 'orange', 2: 'raspberry', 3: 'pineapple', length: 4 }
+var length = push(fruits, 'banana', 'pear', 'coconut')
+
+console.log(fruits)
+// ['apple', 'orange', 'raspberry', 'pineapple', 'banana', 'pear', 'coconut'] (7)
+console.log(length)
+// 7
\ No newline at end of file