def _build(self, X=None):
        """
        Build attributes built_features and built_default.
        """
        if isinstance(self.features, list):
            self.built_features = [
                _build_feature(*f, X=X) for f in self.features
            ]
        else:
            self.built_features = _build_feature(*self.features, X=X)
        self.built_default = _build_transformer(self.default)

 def _build(self, X=None):
        """
        Build attributes built_features and built_default.
        """

        if isinstance(self.features, list):
 
            filtered_list = []
            for obj in self.features:
                if isinstance(obj[0], list):
                    new_cols = [col for col in obj[0] if col not in self.drop_cols]
                   
                    new_tuple = tuple([new_cols] + list(obj[1:]))
                    filtered_list.append(new_tuple)
                else:
                    if obj[0] not in self.drop_cols:
                        filtered_list.append(obj)
            self.features = filtered_list

            self.built_features = [_build_feature(*f, X=X) for f in self.features]
        else:
            self.built_features = _build_feature(*self.features, X=X)
        self.built_default = _build_transformer(self.default)