inmem_transport.go
func (i *InmemTransport) AppendEntriesPipeline(id ServerID, target ServerAddress) (AppendPipeline, error) {
	i.Lock()
	defer i.Unlock()

	peer, ok := i.peers[target]
	if !ok {
		return nil, fmt.Errorf("failed to connect to peer: %v", target)
	}
	pipeline := newInmemPipeline(i, peer, target)
	i.pipelines = append(i.pipelines, pipeline)
	return pipeline, nil
}
func (i *InmemTransport) AppendEntriesPipeline(id ServerID, target ServerAddress) (AppendPipeline, error) {
	i.Lock()
	defer i.Unlock()

	peer, ok := i.peers[target]
	if !ok {
		return nil, fmt.Errorf("failed to connect to peer: %v", target)
	}
	pipeline := newInmemPipeline(i, peer, target)
	i.pipelines = append(i.pipelines, pipeline)
	return pipeline, nil
}
// AppendEntriesPipeline returns an interface that can be used to pipeline
// AppendEntries requests.