code: def set_display_name(self, display_name):
          
          if self.get_display_name_metadata().is_read_only():
              raise errors.NoAccess()
          if not self._is_valid_string(display_name,
                                       self.get_display_name_metadata()):
              raise errors.InvalidArgument()
          self._my_map['displayName']['text'] = display_name
docs: Sets a display name.
  
          arg:    display_name (string): the new display name
          raise:  InvalidArgument - ``display_name`` is invalid
          raise:  NoAccess - ``display_name`` cannot be modified
          raise:  NullArgument - ``display_name`` is ``null``
          *compliance: mandatory -- This method must be implemented.*