'Update an attribute from the client.'

def Update(self, attribute=None, priority=None):

    currently_running = self.Get(self.Schema.CONTENT_LOCK)
    if currently_running:
        flow_obj = aff4.FACTORY.Open(currently_running, token=self.token)
        if (flow_obj and flow_obj.GetRunner().IsRunning()):
            return
    client_id = self.urn.Path().split('/', 2)[1]
    pathspec = self.Get(self.Schema.STAT).pathspec
    flow_urn = flow.GRRFlow.StartFlow(client_id=client_id, flow_name='MultiGetFile', token=self.token, pathspecs=[pathspec], priority=priority)
    self.Set(self.Schema.CONTENT_LOCK(flow_urn))
    self.Close()
    return flow_urn
