docs: def clear_mappers():
      """
      Clears all mappers set up by SA and also clears all custom "id" and
      "slug" attributes inserted by the :func:`mapper` function in this module.
  
      This should only ever be needed in a testing context.
      """
      # Remove our hybrid property constructs.
      for mpr, is_primary in _mapper_registry.items():
          if is_primary:
              for attr_name in ('id', 'slug'):
                  try:
                      attr = object.__getattribute__(mpr.class_, attr_name)
                      if isinstance(attr, hybrid_property):
                          if attr_name == 'id':
                              delattr(mpr.class_, attr_name)
                          else:
                              setattr(mpr.class_, attr_name, attr.descriptor)
                  except AttributeError:
                      pass
      sa_clear_mappers()