Works together with 'mark_as_forwarded' and 'free' methods.

        It makes request to be removed if all replicas request was
        forwarded to freed it.

def mark_as_executed(self, req: Request):
        """
        Works together with 'mark_as_forwarded' and 'free' methods.

        It makes request to be removed if all replicas request was
        forwarded to freed it.
        """
        state = self[req.key]
        state.executed = True
        self._clean(state)