code: def set_marked(self, name: str, marked: bool = False,
                     unmarked: bool = False) -> None:
          
          if marked:
              self._marked[name] = True
          elif unmarked:
              self._marked[name] = False
          else:
              self._marked.pop(name, None)
docs: Add or remove the ``\\Marked`` and ``\\Unmarked`` mailbox
          attributes.
  
          Args:
              name: The name of the mailbox.
              marked: True if the ``\\Marked`` attribute should be added.
              unmarked: True if the ``\\Unmarked`` attribute should be added.