Answer 1

Błack Jesus❕ because at first when list 1 is extended then it's value will be
List1 = [1, 2, 3]
List2 = [2, 3, 4, 5]
# Add List2 to List1
List1.extend(List2)
print(List1)
#[1, 2, 3, 2, 3, 4, 5]
print(List2)
#and list 2 at that time [2,3,4,5]
#Add List1 to List2 now
List2.extend(List1)
#and when you update and extend list 2 then it will extended with new list1 and value will be as
#[2,3,4,5, 1, 2, 3, 2, 3, 4, 5]
print(List1)
print(List2)

This is why the output is like this way

Answer 2

Błack Jesus❕ it's showing expected output check it again
delete trailing space that's invalid for the code might you have copied it from one editor to the app
https://code.sololearn.com/clloOVO8UuBm/?ref=app

Answer 3

Because you added space on line number 4 and 7 after closing bracket ')' That's why it's showing invalid character.

It's working after removing space

https://code.sololearn.com/ctnUm9Arj27s/?ref=app

Answer 4

i think it's solo learn ide problem because i tested this code on my python ide and it's accomplished without error