code: def ellipticity2phi_q(e1, e2):
      
      phi = np.arctan2(e2, e1)/2
      c = np.sqrt(e1**2+e2**2)
      if c > 0.999:
          c = 0.999
      q = (1-c)/(1+c)
      return phi, q
docs: :param e1:
      :param e2:
      :return: