docs: def Fierz_to_EOS_chrom(C, dd, parameters):
      """From Fierz to chromomagnetic EOS basis for Class V.
      dd should be of the form 'sb', 'ds' etc."""
      p = parameters
      V = ckmutil.ckm.ckm_tree(p["Vus"], p["Vub"], p["Vcb"], p["delta"])
      Vtb = V[2,2]
      Vts = V[2,1]
      e = sqrt(4 * pi * parameters['alpha_e'])
      gs = sqrt(4 * pi * parameters['alpha_s'])
      mb = parameters['m_b']
      dic = {"b->s::c7": 16 * pi**2 / mb / e * C["F7gamma" + dd],
              "b->s::c7'": 16 * pi**2 / mb / e * C["F7pgamma" + dd],
              "b->s::c8": 16 * pi**2 / mb / gs * C["F8g" + dd],
              "b->s::c8'": 16 * pi**2 / mb / gs * C["F8pg" + dd]
                  }
      prefactor = sqrt(2)/p['GF']/Vtb/Vts.conj()/4
      return {k: prefactor * v for k,v in dic.items()}