code: def slice_transform(func, self, X, *vargs, **kwargs):
      
      X = X if self.apply_ind is None else X[:, self.apply_ind]
      return func(self, X, *vargs, **kwargs)
docs: Decorator for implementing partial application.
  
      This must decorate the ``transform`` and ``grad`` methods of basis objects
      if the ``slice_init`` decorator was used.