Why isinstance() not recognising list as a type?

Question

Very basic but I can't think what I'm doing wrong so hoping maybe it's a syntax change I'm not yet aware of. This line:

if isinstance(x, list):

Throws this error:

TypeError: isinstance() arg 2 must be a type or tuple of types

So why isinstance() not recognising list as a type?

Answer 1

You probably overwritten list somewhere in your program:

>>> isinstance("", list)
False
>>> list = 123
>>> isinstance("", list)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: isinstance() arg 2 must be a type or tuple of types
>>>