code: def WriteProtoFile(self, printer):
          
          self.Validate()
          client_info = self.__client_info
          printer('// Generated services for %s version %s.',
                  client_info.package, client_info.version)
          printer()
          printer('syntax = "proto2";')
          printer('package %s;', self.__package)
          printer('import "%s";', client_info.messages_proto_file_name)
          printer()
          for name, method_info_map in self.__service_method_info_map.items():
              self.__WriteProtoServiceDeclaration(printer, name, method_info_map)
docs: Write the services in this registry to out as proto.