List Methods

extend()

Append elements from an iterable to the end of the list.

list.extend(iterable)

list.extend() iterates over iterable and appends each element individually to the end of the list.

This is equivalent to iterating with a for loop and calling append() on each item, but implemented in optimized C.

Parameters

Name	Description
iterable	Any iterable object (list, tuple, set, string, or generator) whose items will be appended.

None — the list is extended in place.

Run it and change it

primary = ["red", "green"]
secondary = ["yellow", "cyan"]
primary.extend(secondary)
print(primary)

Extending strings: If you pass a string to extend(), it unpacks each individual character into the list: [].extend('cat') becomes ['c', 'a', 't'].
In-place operator: The += operator on lists (e.g. list_a += list_b) calls extend() under the hood.