docs: def _BernI_to_FormFlavor_I(C, qq):
      """From BernI to FormFlavorI basis for $\Delta F=2$ operators.
      `qq` should be 'sb', 'db', 'ds' or 'uc'"""
      qqf = qq[::-1] # FormFlavour uses "bs" instead of "sb" etc.
      if qq in ['sb', 'db', 'ds']:
          return {
              'CVLL_' + 2*qqf: C["1" + 2*qq],
              'CSLL_' + 2*qqf: C["2" + 2*qq] + 1 / 2 * C["3" + 2*qq],
              'CTLL_' + 2*qqf: -1 / 8 * C["3" + 2*qq],
              'CVLR_' + 2*qqf: -1 / 2 * C["5" + 2*qq],
              'CVRR_' + 2*qqf: C["1p" + 2*qq],
              'CSRR_' + 2*qqf: C["2p" + 2*qq] + 1 / 2 * C["3p" + 2*qq],
              'CTRR_' + 2*qqf: -1 / 8 * C["3p" + 2*qq],
              'CSLR_' + 2*qqf: C["4" + 2*qq]
              }
      elif qq == 'cu':
          return {
              'CVLL_' + 2*qq: C["1" + 2*qq].conjugate(),
              'CSLL_' + 2*qq: C["2" + 2*qq] + 1 / 2 * C["3" + 2*qq].conjugate(),
              'CTLL_' + 2*qq: -1 / 8 * C["3" + 2*qq].conjugate(),
              'CVLR_' + 2*qq: -1 / 2 * C["5" + 2*qq].conjugate(),
              'CVRR_' + 2*qq: C["1p" + 2*qq].conjugate(),
              'CSRR_' + 2*qq: C["2p" + 2*qq].conjugate() + 1 / 2 * C["3p" + 2*qq].conjugate(),
              'CTRR_' + 2*qq: -1 / 8 * C["3p" + 2*qq],
              'CSLR_' + 2*qq: C["4" + 2*qq].conjugate()
              }
      else:
          raise ValueError("{} not in FormFlavor_I".format(qq))