code: def copy_from_model(cls, model_name, reference, **kwargs):
          
          if isinstance(reference, cls):
              settings = reference.__dict__.copy()
              settings.pop('model')
          else:
              settings = _get_model_info(reference)
              settings.pop('model_name')
  
          settings.update(kwargs)
          settings['reference'] = reference
  
          return cls(model_name, **settings)
docs: Set-up a user-defined grid using specifications of a reference
          grid model.
  
          Parameters
          ----------
          model_name : string
              name of the user-defined grid model.
          reference : string or :class:`CTMGrid` instance
              Name of the reference model (see :func:`get_supported_models`),
              or a :class:`CTMGrid` object from which grid set-up is copied.
          **kwargs
              Any set-up parameter which will override the settings of the
              reference model (see :class:`CTMGrid` parameters).
  
          Returns
          -------
          A :class:`CTMGrid` object.