docs: def detunings_code(Neu, Nl, pairs, omega_levelu, iu0, ju0):
      r"""Get the code to calculate the simplified detunings.
  
      >>> Ne = 6
      >>> Nl = 2
      >>> omega_level = [0.0, 100.0, 100.0, 200.0, 200.0, 300.0]
      >>> xi = np.zeros((Nl, Ne, Ne))
      >>> coup = [[(1, 0), (2, 0)], [(3, 0), (4, 0), (5, 0)]]
      >>> for l in range(Nl):
      ...     for pair in coup[l]:
      ...         xi[l, pair[0], pair[1]] = 1.0
      ...         xi[l, pair[1], pair[0]] = 1.0
  
      >>> aux = define_simplification(omega_level, xi, Nl)
      >>> u, invu, omega_levelu, Neu, xiu = aux
      >>> omega_min, iu0, ju0 = find_omega_min(omega_levelu, Neu, Nl, xiu)
      >>> pairs = detunings_indices(Neu, Nl, xiu)
      >>> print(detunings_code(Neu, Nl, pairs, omega_levelu, iu0, ju0))
          delta1_2_1 = detuning_knob[0]
          delta2_3_1 = detuning_knob[1]
          delta2_4_1 = detuning_knob[1] + (-100.0)
      <BLANKLINE>
  
      """
      code_det = ""
      for l in range(Nl):
          for pair in pairs[l]:
              iu, ju = pair
              code_det += "    delta"+str(l+1)
              code_det += "_"+str(iu+1)
              code_det += "_"+str(ju+1)
              code_det += " = detuning_knob["+str(l)+"]"
              corr = -omega_levelu[iu]+omega_levelu[iu0[l]]
              corr = -omega_levelu[ju0[l]]+omega_levelu[ju] + corr
  
              if corr != 0:
                  code_det += " + ("+str(corr)+")"
              code_det += "\n"
      return code_det