complexity of append python code example

Example 1: python add all values of another list

a = [1, 2, 3]
b = [4, 5, 6]
a += b
# another way: a.extend(b)

Example 2: how to extend an array python

my_list = ['geeks', 'for'] 
another_list = [6, 0, 4, 1] 
my_list.extend(another_list)