Why output 3 but no 2?

Question

a = [1,2]
b=a
a.append(1)
print(len(b))

Answer 1

so b is a = True

Answer 2

Lol thanks bro

Answer 3

Because of "b=a"...... "b" and "a" refer to the same list...print their id's to check.

Answer 4

lol...didn't think to suggest using "is"....but yes...that correct.