Internal Implementations of List.extend() and List.append() operations in Python

Let’s take a deep dive into the internal implementation of List.extend() & List.append() operations:

Suppose the list nums[] contains 7 integer elements, and we're about to execute lines as below:

Sample 1

result=[]
    for i in range(n):
        result.append(nums[0])
        result.append(nums[1])
return result

Sample 2

result=[]
    for i in range(n):
        result.extend([nums[0],nums[1]])
return result

Analysis of Internal Implementation

Sample 1

• When we execute result.append(nums[0]),result.append(nums[1]), the internal implementation will be like as below:

1. List result get reference to num[0]which actually pointed to the integer instance 'int1'
2. Then list result get reference to num[1]which actually pointed to the integer instance 'int2'

Sample 2

• When we execute result.extend([nums[0],nums[1]]), the internal implementation will be like as below:

1. Contents inside the parentheses of .extend() function can be treated as a temp list which actually pointed to the same integer objects as list nums
2. Then, the list result receive those references to those integers through that temp list

This post is also a complement to my previous post:
https://dev.to/effylh/leetcode-1470-shuffle-the-array-3ok5