code: func splitMethodName(fullMethodName string) (string, string) {
  	fullMethodName = strings.TrimPrefix(fullMethodName, "/") // remove leading slash
  	if i := strings.Index(fullMethodName, "/"); i >= 0 {
  		return fullMethodName[:i], fullMethodName[i+1:]
  	}
  	return "unknown", "unknown"
  }
docs: // splitMethodName is borrowed directly from
  // `grpc-ecosystem/go-grpc-prometheus/util.go` and is used to extract the
  // service and method name from the `method` argument to
  // a `UnaryClientInterceptor`.