[Douglas]'s sister [Ann] asked him to play cards with her, He did n't want to, he wanted to go ride bikes with his brother [John] instead.
('John', 'Ann')
[Douglas]'s sister [Ann] asked him to play cards with her, He did n't want to, he wanted to go ride bikes with his brother [John] instead.
[{('John', 'sister', 'Ann'): [('John', 'brother', 'Douglas'), ('Douglas', 'sister', 'Ann')]}]
['brother', 'sister']