[Clarence] took his grandson [Jeff] to the zoo. [Jeff]'s brother [Robert] went to the aquarium instead.
('Clarence', 'Robert')
[Clarence] took his grandson [Jeff] to the zoo. [Jeff]'s brother [Robert] went to the aquarium instead.
[{('Clarence', 'grandson', 'Robert'): [('Clarence', 'grandson', 'Jeff'), ('Jeff', 'brother', 'Robert')]}]
['grandson', 'brother']