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 __deepcopy__(self, memo=None):
      clone = type(self)()
      clone.MergeFrom(self)
      return clone
  
label_desc: Use image node_id 1 for calling the Message obj's underlying member method code with example usage: obj.__deepcopy__(memo) and returns: clone