Add extend() for collections.deque in python (#7775)

* Added pop.md

* Added extend.md

* minor changes

* Removed pop.md

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Author: Aaravthk

content/python/concepts/deque/terms/extend/extend.md

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+---
+Title: 'extend()'
+Description: 'Adds multiple elements to the right end of a deque from any iterable.'
+Subjects:
+  - 'Computer Science'
+  - 'Data Science'
+Tags:
+  - 'Algorithms'
+  - 'Collections'
+  - 'Data Structures'
+  - 'Deques'
+CatalogContent:
+  - 'learn-python-3'
+  - 'paths/computer-science'
+---
+
+The **`extend()`** method adds multiple elements to the right end of a `deque` from any iterable (like a [list](https://www.codecademy.com/resources/docs/python/lists), [tuple](https://www.codecademy.com/resources/docs/python/tuples), or another deque). It modifies the deque in place and returns `None`.
+
+## Syntax
+
+```pseudo
+deque.extend(iterable)
+```
+
+**Parameters:**
+
+- `iterable`: A sequence or iterable whose elements will be added to the right end of the deque.
+
+**Return value:**
+
+This method does not return any value. It modifies the deque in-place.
+
+## Example
+
+In this example, `extend()` adds elements from a list and another deque to the right end of a deque:
+
+```py
+from collections import deque
+
+# Create a deque
+dq = deque([1, 2, 3])
+
+# Extend it
+dq.extend([4, 5, 6])
+print("Extending with list: ", dq)
+
+#Extend it using another deque
+dq.extend(deque([7, 8, 9]))
+print("Extending with another deque: ", dq)
+```
+
+This example results in the following output:
+
+```shell
+Extending with list: deque([1, 2, 3, 4, 5, 6])
+Extending with another deque: deque([1, 2, 3, 4, 5, 6, 7, 8, 9])
+```
+
+## Codebyte Example: Extending a deque with a list and a tuple
+
+In this example, `extend()` adds elements from a list and a tuple, demonstrating its ability to handle different iterables:
+
+```codebyte/python
+from collections import deque
+
+# Create a deque with some initial elements
+fruits = deque(["apple","banana"])
+
+print("Initital deque:", fruits)
+
+# Add multiple elements to the right using extend()
+fruits.extend(["cherry", "date", "elderberry"])
+
+# Extend again using a tuple
+fruits.extend(("fig", "grape"))
+print("Deque after extending with a tuple:", fruits)
+```