code: def _compute_dk_dy(self, y, n):
          
          p = fixed_poch(1.0 - self.params[1] - n, n)
          return p * y**(-self.params[1] - n)
docs: Evaluate the derivative of the outer form of the RQ kernel.
          
          Parameters
          ----------
          y : :py:class:`Array`, (`M`,)
              `M` inputs to evaluate at.
          n : non-negative scalar int
              Order of derivative to compute.
          
          Returns
          -------
          dk_dy : :py:class:`Array`, (`M`,)
              Specified derivative at specified locations.