Почему в консоль выводится исходный список

Question

arr = [4,3,1,2]
arr[0], arr[arr[0]-1] == arr[arr[0]-1], arr[0]
print(arr)

Answer 1

# Почему в консоль выводится исходный список
# Why is the original list displayed in the console?

arr = [4,3,1,2]
print(arr[0], arr[3] == arr[3], arr[0])
print(arr)

# the equality operator == checks if two values are equal
print(1 == 4)

# the assignment operator = assigns a value to a variable
num = 5
print(num)

arr[0] = 10
print(arr)

Answer 2

Although line 2 looks like is comparing values, actually it is not. It prints nothing and didn't change the original list.

Line 2's explanation.
arr[0], arr[arr[0]-1] == arr[arr[0]-1], arr[0]
4, arr[4-1] == arr[4-1], 4
4, arr[3] == arr[3], 4
4, 2 == 2, 4
(4, True, 4) # line 2 is evaluated into a tuple

After line 2 is evaluated it does nothing and original list arr is unchanged.
Thus printing arr return the original list.

Answer 3

По тому что Вы скорее всего спутали оператор сравнения "==" с оператором присваивания "=".