code: def adjoint(self):
          
          if self._adjoint is not None:
              return self._adjoint
  
          kwargs = self._extra_kwargs.copy()
          kwargs['range'] = self.domain
          self._adjoint = RayTransform(self.range, self.geometry,
                                       impl=self.impl,
                                       use_cache=self.use_cache,
                                       **kwargs)
          return self._adjoint
docs: Adjoint of this operator.
  
          Returns
          -------
          adjoint : `RayTransform`