docs: def zeeman_energies(fine_state, Bz):
      r"""Return Zeeman effect energies for a given fine state and\
      magnetic field.
  
      >>> ground_state = State("Rb", 87, 5, 0, 1/Integer(2))
      >>> Bz = 200.0
      >>> Bz = Bz/10000
      >>> for f_group in zeeman_energies(ground_state, Bz):
      ...     print(f_group)
      [-2.73736448508248e-24 -2.83044285506388e-24 -2.92352122504527e-24]
      [1.51284728917866e-24 1.60555650110849e-24 1.69826571303833e-24
       1.79097492496816e-24 1.88368413689800e-24]
  
      """
      element = fine_state.element
      isotope = fine_state.isotope
      N = fine_state.n
      L = fine_state.l
      J = fine_state.j
  
      energiesZeeman = []
      for i, F in enumerate(fine_state.fperm):
          gL, gS, gI, gJ, gF = lande_g_factors(element, isotope, L, J, F)
          energiesF = []
          hyperfine_level = State(element, isotope, N, L, J, F)
          for MF in range(-F, F+1):
              unperturbed_energy = hbar*hyperfine_level.omega
              energyMF = unperturbed_energy + muB*gF*MF*Bz
              energiesF += [energyMF]
          energiesZeeman += [array(energiesF)]
  
      return energiesZeeman