code: def _co_moving2angle(self, x, y, idex):
          
          T_z = self._T_z_list[idex]
          #T_z = self._cosmo_bkg.T_xy(0, z_lens)
          theta_x = x / T_z
          theta_y = y / T_z
          return theta_x, theta_y
docs: transforms co-moving distances Mpc into angles on the sky (radian)
  
          :param x: co-moving distance
          :param y: co-moving distance
          :param z_lens: redshift of plane
          :return: angles on the sky