List Methods

insert()

Insert an item at a specified index.

list.insert(index, item)

list.insert() inserts item at the given index, shifting all subsequent elements one position to the right.

Inserting at index 0 prepends the item to the beginning of the list.

Parameters

Name	Description
index	The position where the new element should be inserted.
item	The item to insert.

None — the list is modified in place.

Run it and change it

numbers = [1, 2, 4, 5]
numbers.insert(2, 3)
print(numbers)

Out of bounds indices: An index larger than the list length appends the item to the end; a negative index smaller than -len(list) prepends it to the front without error.
Performance consideration: Inserting at the front (index 0) requires shifting all elements and is O(n). For frequent insertions at both ends, use collections.deque.