[Robert] wanted to go to the bookstore with his grandfather, [Clarence], but [Robert]'s brother, [Jacob], told him that [Clarence] wo n't be able to come today.
('Clarence', 'Jacob')
[Robert] wanted to go to the bookstore with his grandfather, [Clarence], but [Robert]'s brother, [Jacob], told him that [Clarence] wo n't be able to come today.
[{('Clarence', 'grandson', 'Jacob'): [('Clarence', 'grandson', 'Robert'), ('Robert', 'brother', 'Jacob')]}]
['grandson', 'brother']