docs: def _parse_names_set(feature_names):
          """Helping function of `_parse_feature_names` that parses a set of feature names."""
          feature_collection = OrderedDict()
          for feature_name in feature_names:
              if isinstance(feature_name, str):
                  feature_collection[feature_name] = ...
              else:
                  raise ValueError('Failed to parse {}, expected string'.format(feature_name))
          return feature_collection