docs: def JMS_to_FormFlavor_chrom(C, qq, parameters):
      """From JMS to chromomagnetic FormFlavor basis for Class V.
      qq should be of the form 'sb', 'ds', 'uu', mt (mu tau), em (e mu) etc."""
      e = sqrt(4 * pi * parameters['alpha_e'])
      gs = sqrt(4 * pi * parameters['alpha_s'])
      if qq[0] in dflav.keys():
          s = dflav[qq[0]]
          b = dflav[qq[1]]
          return {
              'CAR_' + qq : C['dgamma'][s, b] / e,
              'CGR_' + qq : C['dG'][s, b] / gs,
              'CAL_'  + qq : C['dgamma'][b, s].conj() / e,
              'CGL_' + qq : C['dG'][b, s].conj() / gs,
                  }
      if qq[0] in llflav.keys():
          l1 = llflav[qq[0]]
          l2 = llflav[qq[1]]
          return {
              'CAR_' + qq : C['egamma'][l1, l2] / e,
              'CAL_' + qq : C['egamma'][l2, l1].conj() / gs,
                  }
      if qq[0] in uflav.keys():
          u = uflav[qq[0]]
          c = uflav[qq[1]]
          return {
              'CAR_' + qq : C['ugamma'][u, c] / e,
              'CGR_' + qq : C['uG'][u, c] / gs,
              'CAL_'  + qq : C['ugamma'][c, u].conj() / e,
              'CGL_' + qq : C['uG'][c, u].conj() / gs,
                  }
      else:
          return 'not in FormFlav_chrom'