code: def WriteFlowObject(self, flow_obj):
      
      if flow_obj.client_id not in self.metadatas:
        raise db.UnknownClientError(flow_obj.client_id)
  
      clone = flow_obj.Copy()
      clone.last_update_time = rdfvalue.RDFDatetime.Now()
      self.flows[(flow_obj.client_id, flow_obj.flow_id)] = clone
docs: Writes a flow object to the database.