Python ABC WTF

I was playing with some python code recently, and something... kind of caught me offguard. (Well, more like I misunderstood how the API works). Consider the following:

from abc import ABC
class MyAbCls(ABC): pass
class MyRealCls(MyAbCls): pass
class AnotherMyRealCls(MyRealCls): pass

my_real_in=MyRealCls()
another_real_in=AnotherMyRealCls()

When confronted with issubclass, my immediate expectation on how it should work is:

# RETURNS FALSE!
assert issubclass(my_real_in, MyAbCls)

Then it hit me. issubclass expects classes as arguments. I should have been using isinstance instead. e.g.:

assert isinstance(my_real_in, MyAbCls)
assert isinstance(another_real_in, MyRealCls)
assert isinstance(another_real_in, MyAbCls)

assert issubclass(type(my_real_in), MyAbCls)