docs: def find_base_generic(type_):
      """Locates the underlying generic whose structure and behavior are known.
  
      For example, the base generic of a type that inherits from `typing.Mapping[T, int]`
      is `typing.Mapping`.
      """
      for t in type_.__mro__:
          if t.__module__ == typing.__name__:
              return first_origin(t)