code: def _call_numpy(self, x):
          
          assert isinstance(x, np.ndarray)
  
          if self.halfcomplex:
              return np.fft.rfftn(x, axes=self.axes)
          else:
              if self.sign == '-':
                  return np.fft.fftn(x, axes=self.axes)
              else:
                  # Need to undo Numpy IFFT scaling
                  return (np.prod(np.take(self.domain.shape, self.axes)) *
                          np.fft.ifftn(x, axes=self.axes))
docs: Return ``self(x)`` using numpy.
  
          See Also
          --------
          DiscreteFourierTransformBase._call_numpy