def encrypters(self):
        """A ``set`` containing all key ids (if any) to which this message was encrypted."""
        return set(m.encrypter for m in self._sessionkeys if isinstance(m, PKESessionKey))
def encrypters ( self ) : return set ( m . encrypter for m in self . _sessionkeys if isinstance ( m , PKESessionKey ) )
A ``set`` containing all key ids (if any) to which this message was encrypted.