[Dennis] asked his father, [Nicholas] to help him build a birdhouse. [Dennis]'s grandfather, [Clarence], was part of a famous band.
('Nicholas', 'Clarence')
[Dennis] asked his father, [Nicholas] to help him build a birdhouse. [Dennis]'s grandfather, [Clarence], was part of a famous band.
[{('Nicholas', 'father', 'Clarence'): [('Nicholas', 'son', 'Dennis'), ('Dennis', 'grandfather', 'Clarence')]}]
['son', 'grandfather']