get al list of all dependencies for the given item "dep"

def _get_all_refs(self, dep, handled_refs=None):
        """
        get al list of all dependencies for the given item "dep"
        """
        if handled_refs is None:
            handled_refs = [dep]
        else:
            if dep in handled_refs:
                return []
        res = []
        if dep in self.future_values_key_item:
            res.extend(
                self.future_values_key_item[dep]["dependencies"].values())
            add = []
            for h_d in res:
                add.extend(self._get_all_refs(h_d, handled_refs))
            res.extend(add)
        return list(set(res))