def normalize_fields(self, path_tree):
    if (len(path_tree) > 0):
        (yield from path_tree.keys())
    else:
        for field in self.keys():
            if ((self._default_fields is None) or (field in self._default_fields)):
                (yield field)
def normalize_fields(self, path_tree):
    if (len(path_tree) > 0):
        (yield from path_tree.keys())
    else:
        for field in self.keys():
            if ((self._default_fields is None) or (field in self._default_fields)):
                (yield field)