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