kubernetes/vendor/go.etcd.io/etcd/server/v3/etcdserver/api/v3rpc/util.go

var toGRPCErrorMap …

func togRPCError(err error) error { … }

func isClientCtxErr(ctxErr error, err error) bool { … }

// in v3.4, learner is allowed to serve serializable read and endpoint status
func isRPCSupportedForLearner(req interface{ … }