def _children_to_string(self, level, string_lst):
for (node_link, node) in self._nodes.items():<EOL><INDENT>string_lst.append("<STR_LIT>" % ('<STR_LIT:U+0020>' * level, node_link))<EOL>node._children_to_string(level+<NUM_LIT:2>, string_lst)<EOL><DEDENT>
Args:
    level:
    string_lst: