Deletes a list of client messages from the db.

def DeleteClientActionRequests(self, requests):
    """Deletes a list of client messages from the db."""
    if not requests:
      return

    to_delete = []
    for r in requests:
      to_delete.append((r.client_id, r.flow_id, r.request_id))

    if len(set(to_delete)) != len(to_delete):
      raise ValueError(
          "Received multiple copies of the same message to delete.")

    self._DeleteClientActionRequest(to_delete)