docs: def Fierz_to_JMS_chrom(C, qq):
      """From chromomagnetic Fierz to JMS basis for Class V.
      qq should be of the form 'sb', 'ds' etc."""
      if qq[0] in dflav:
          s = dflav[qq[0]] + 1
          b = dflav[qq[1]] + 1
          return {'dgamma_{}{}'.format(s, b): C['F7gamma' + qq],
                  'dG_{}{}'.format(s, b): C['F8g' + qq],
                  'dgamma_{}{}'.format(b, s): C['F7pgamma' + qq].conjugate(),
                  'dG_{}{}'.format(b, s): C['F8pg' + qq].conjugate(),
                  }
      else:
          u = uflav[qq[0]] + 1
          c = uflav[qq[1]] + 1
          return {'ugamma_{}{}'.format(u, c): C['F7gamma' + qq],
                  'uG_{}{}'.format(u, c): C['F8g' + qq],
                  'ugamma_{}{}'.format(c, u): C['F7pgamma' + qq].conjugate(),
                  'uG_{}{}'.format(c, u): C['F8pg' + qq].conjugate(),
                  }