How to explain the first expression?

Question

>>> 3 in [1, 2, 3] == [1, 2, 3]
True

>>> (3 in [1, 2, 3]) == [1, 2, 3]
False

>>> 3 in ([1, 2, 3] == [1, 2, 3])
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: argument of type 'bool' is not iterable

Answer 1

The operator in needs an iterable on the right side.
But [1,2,3] ==[1,2,3] evals to True.
First expression:
[1,2,3] is truthy like all variables that are not empty, None or 0. Convince yourself and use [ ] instead [1,2,3].