docs: def scale_dict_wet(C):
      """To account for the fact that arXiv:Jenkins:2017jig uses a flavour
      non-redundant basis in contrast to WCxf, symmetry factors of two have to
      be introduced in several places for operators that are symmetric
      under the interchange of two currents."""
      return {k: v / _scale_dict[k] for k, v in C.items()}