Reads flows that were started by a given flow from the database.

def ReadChildFlowObjects(self, client_id, flow_id):
    """Reads flows that were started by a given flow from the database."""
    res = []
    for flow in itervalues(self.flows):
      if flow.client_id == client_id and flow.parent_flow_id == flow_id:
        res.append(flow)
    return res