class_docstr: Abstract base class for protocol messages.
  
  Protocol message classes are almost always generated by the protocol
  compiler.  These generated types subclass Message and implement the methods
  shown below.
code: def __reduce__(self):
      message_descriptor = self.DESCRIPTOR
      if message_descriptor.containing_type is None:
          return type(self), (), self.__getstate__()
      # the message type must be nested.
      # Python does not pickle nested classes; use the symbol_database on the
      # receiving end.
      container = message_descriptor
      return (
          _InternalConstructMessage,
          (container.full_name,),
          self.__getstate__(),
      )
  
label_desc: Use image node_id 28 for calling the Message obj's underlying member method code with example usage: obj.__reduce__() and returns: _InternalConstructMessage,  container,  self, type,  ,  self