code: func FindMethodForService(s *pb.ServiceDescriptorProto, name string) int {
  	for i, x := range s.GetMethod() {
  		if x.GetName() == name {
  			return i
  		}
  	}
  	return -1
  }
docs: ////////////////////////////////////////////////////////////////////////////////
  // ServiceDescriptorProto
  // FindMethodForService searches for a MethodDescriptorProto by name.