code: def alpha(self, theta_x, theta_y, kwargs_lens, k=None):
          
          beta_x, beta_y = self.ray_shooting(theta_x, theta_y, kwargs_lens)
          alpha_x = theta_x - beta_x
          alpha_y = theta_y - beta_y
          return alpha_x, alpha_y
docs: reduced deflection angle
  
          :param theta_x: angle in x-direction
          :param theta_y: angle in y-direction
          :param kwargs_lens: lens model kwargs
          :return: