he features to use: either from an annotation/annotation getter or from
        # features or a features getter

        if self.fromann is not None:
            if isinstance(self.fromann, Annotation):
                fromfeats = self.fromann.features
            else:
                ann = self.fromann(succ)
                if ann is None:
                    if self.silent_fail:
                        return
                    else:
                        raise Exception(&#34;No matching source annota