[Andrea] is a woman with a sister named [Janet]. [April] is looking for a good gift for her sister [Janet].
('April', 'Andrea')
[April] is looking for a good gift for her sister [Janet]. [Andrea] is a woman with a sister named [Janet].
[{('April', 'sister', 'Andrea'): [('April', 'sister', 'Janet'), ('Janet', 'sister', 'Andrea')]}]
['sister', 'sister']