docs: def ray_shooting(self, x, y, kwargs, k=None):
          """
          maps image to source position (inverse deflection)
          :param x: x-position (preferentially arcsec)
          :type x: numpy array
          :param y: y-position (preferentially arcsec)
          :type y: numpy array
          :param kwargs: list of keyword arguments of lens model parameters matching the lens model classes
          :param k: only evaluate the k-th lens model
          :return: source plane positions corresponding to (x, y) in the image plane
          """
          dx, dy = self.alpha(x, y, kwargs, k=k)
          return x - dx, y - dy