[Nicholas] bought a book for his son [Dennis]. [Nicholas] and his sister [Nancy] went to the ice skating rink. [Nicholas] fell down and [Nancy] laughed at him.
('Dennis', 'Nancy')
[Nicholas] bought a book for his son [Dennis]. [Nicholas] and his sister [Nancy] went to the ice skating rink. [Nicholas] fell down and [Nancy] laughed at him.
[{('Dennis', 'aunt', 'Nancy'): [('Dennis', 'father', 'Nicholas'), ('Nicholas', 'sister', 'Nancy')]}]
['father', 'sister']