Type Error: “'types.GenericAlias' object is not …” after using  instead of () on a container type
As of Python 3.9 / PEP 585 the builtin containers are type hint generics. For example,
list[str] is the annotation for “a list of strings”.
Typos mixing up idexing
 and calling
() no longer fail, but create a
types.GenericAlias. This leads to obscure error
Type Error: “'types.GenericAlias' object is not ...” when the result is used.
>>> values = list[range(5)] # typo is here >>> for value in values: # error occurs here ... print(value)