Why does list.append evaluate to false in a boolean context? [duplicate]

Answer 1

because .append method returns None, therefore not None evaluates to True. Python on error usually raises an error:

>>> a = ()
>>> a.append(5)
Traceback (most recent call last):
  File "", line 1, in 
    a.append(5)
AttributeError: 'tuple' object has no attribute 'append'