A start on how to work around the annoying python behavior that isinstance doesn't work with generics in Python

type_workaround.py

from fastcore.all import *
from typing import _SpecialForm,_GenericAlias,Optional,Union

@patch
def __instancecheck__(self:_SpecialForm, typs): return isinstance(self, typs)
@patch(cls_method=True)
def __subclasscheck__(self:_SpecialForm, cls): return type.__subclasscheck__(self, cls)
@patch
def __subclasscheck__(self:_GenericAlias, cls):
    return issubclass(cls.__origin__ if isinstance(cls, _GenericAlias) else cls, self.__origin__)

# test:
a = Optional[int]
isinstance(a,Optional),isinstance(a,int)