Type of list

Question

Why when write a=[20] is type work normaly, but when we write a=list[20] is output - "object is not subscriptale?

Answer 1

Try a = list(20)

Answer 2

When write a=list(20) is output - " 'int' object is not iterable

Answer 3

print(type(list('20')))

Answer 4

Ok, but why a=list[20] not work?