add popleft() entry

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

@@ -0,0 +1,73 @@
+---
+Title: '.popleft()'
+Description: 'Removes and returns an element from the left end of a deque object in Python.'
+Subjects:
+  - 'Code Foundations'
+  - 'Data Structures'
+Tags:
+  - 'Collections'
+  - 'Deques'
+  - 'Methods'
+  - 'Queues'
+CatalogContent:
+  - 'learn-python-3'
+  - 'python-data-structures'
+---
+
+The **`deque.popleft()`** method removes and returns the element from the left end (first element) of a `deque` object. A [`deque`](https://www.codecademy.com/resources/docs/python/collections-module/deque) (double-ended queue) allows elements to be added or removed efficiently from both ends. Calling `.popleft()` on an empty deque raises an `IndexError`.
+
+## Syntax
+
+```pseudo
+deque.popleft()
+```
+
+**Parameters:**
+
+The `.popleft()` method does not take any parameters.
+
+**Return value:**
+
+Returns the element removed from the left end of the deque.
+
+## Example
+
+In this example, the first element is removed from the left end of a deque:
+
+```py
+from collections import deque
+
+# Create a deque with several elements
+queue = deque(['apple', 'banana', 'cherry'])
+
+# Remove the leftmost element
+left_item = queue.popleft()
+print("Removed element:", left_item)
+print("Deque after popleft():", queue)
+```
+
+The output of this code is:
+
+```shell
+Removed element: apple
+Deque after popleft(): deque(['banana', 'cherry'])
+```
+
+## Codebyte Example
+
+In this example, a deque is used to simulate a queue of customers. The first customer is served using `.popleft()`:
+
+```codebyte/python
+from collections import deque
+
+# Queue of customers
+customers = deque(["Alice", "Bob", "Charlie", "Diana"])
+
+print("Queue before serving:", list(customers))
+
+# Serve the first customer
+served_customer = customers.popleft()
+print("Serving customer:", served_customer)
+
+print("Queue after serving:", list(customers))
+```