text: from __future__ import annotations
  import typing as t
  
  GenericContext = t.Dict[str, t.Any]
  ImmutableContext = t.Mapping[str, t.Any]
  
  T = t.TypeVar('T')
  
  SequenceOrT = t.Union[t.Sequence[T], T]
  
  Prefix = str
  Prefixes = t.Tuple[Prefix, ...]
  
  MappingSet = t.Set[str]
  OptionalMappingSet = t.Optional[MappingSet]
  
  InitKwargs = t.Dict[str, t.Any]
  OptionalInitKwargs = t.Optional[InitKwargs]
  