func (s *Orchestrator) eventFilter(event *event.Event) func(wf *process.Process, node *process.Process_Node) (bool, error) {
    return func(wf *process.Process, node *process.Process_Node) (bool, error) {
        if e := node.GetEvent(); e != nil {
            return e.InstanceHash.Equal(event.InstanceHash) && e.EventKey == event.Key, nil
        }