>>> from typing import Generic, TypeVar
>>> T = TypeVar("T")
>>> U = TypeVar("U")
>>> class X(Generic[T], Generic[U]): pass
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/jelle/py/cpython/Lib/typing.py", line 1088, in _generic_init_subclass
    raise TypeError(
TypeError: Cannot inherit from Generic[...] multiple types.