code: def AddDescriptor(self, desc):
      
      if not isinstance(desc, descriptor.Descriptor):
        raise TypeError('Expected instance of descriptor.Descriptor.')
  
      self._descriptors[desc.full_name] = desc
      self._AddFileDescriptor(desc.file)
docs: Adds a Descriptor to the pool, non-recursively.
  
      If the Descriptor contains nested messages or enums, the caller must
      explicitly register them. This method also registers the FileDescriptor
      associated with the message.
  
      Args:
        desc: A Descriptor.