[Nicholas] and his sister [Nancy] love to play video games. [Nancy] is looking for a good gift for her sister [Theresa].
('Nicholas', 'Theresa')
[Nicholas] and his sister [Nancy] love to play video games. [Nancy] is looking for a good gift for her sister [Theresa].
[{('Nicholas', 'sister', 'Theresa'): [('Nicholas', 'sister', 'Nancy'), ('Nancy', 'sister', 'Theresa')]}]
['sister', 'sister']