code: def _call(self, x, out=None):
          
          if out is None:
              out = self.range.element()
  
          # TODO: this pipes CUDA arrays through NumPy. Write native operator.
          with writable_array(out) as out_arr:
              finite_diff(x.asarray(), axis=self.axis, dx=self.dx,
                          method=self.method, pad_mode=self.pad_mode,
                          pad_const=self.pad_const, out=out_arr)
          return out
docs: Calculate partial derivative of ``x``.