content: import enum
  from typing import Mapping, Union
  
  from kopf.structs import callbacks
  
  
  class MetaFilterToken(enum.Enum):
      """ Tokens for filtering by annotations/labels. """
      PRESENT = enum.auto()
      ABSENT = enum.auto()
  
  
  # For exporting to the top-level package.
  ABSENT = MetaFilterToken.ABSENT
  PRESENT = MetaFilterToken.PRESENT
  
  # Filters for handler specifications (not the same as the object's values).
  MetaFilter = Mapping[str, Union[None, str, MetaFilterToken, callbacks.MetaFilterFn]]
  