Creating with Generic[T] Interfaces #47

...
    class MyInterface(Generic[T], Interface):  # Does not (currently) derive from ABC to avoid serialization issues.
  File "C:\Users\adishavit\Miniconda3\envs\roomassignments\lib\site-packages\interface\interface.py", line 106, in __new__
    signatures = _merge_parent_signatures(bases)
  File "C:\Users\adishavit\Miniconda3\envs\roomassignments\lib\site-packages\interface\interface.py", line 91, in _merge_parent_signatures
    return merge(filter(None, (getattr(b, "_signatures") for b in bases)))
  File "C:\Users\adishavit\Miniconda3\envs\roomassignments\lib\site-packages\interface\functional.py", line 52, in merge
    dicts = list(dicts)
  File "C:\Users\adishavit\Miniconda3\envs\roomassignments\lib\site-packages\interface\interface.py", line 91, in <genexpr>
    return merge(filter(None, (getattr(b, "_signatures") for b in bases)))
AttributeError: type object 'Generic' has no attribute '_signatures'