<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def alpha(self, theta_x, theta_y, kwargs_lens, k=None):
 """ reduced deflection angle :param theta_x: angle in x-direction :param theta_y: angle in y-direction :param kwargs_lens: lens model kwargs :return: """

        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