[Clarence] went bike riding his grandson [Tony]. [Tony]'s father [Dale] was skateboarding.
('Dale', 'Clarence')
[Clarence] went bike riding his grandson [Tony]. [Tony]'s father [Dale] was skateboarding.
[{('Dale', 'father', 'Clarence'): [('Dale', 'son', 'Tony'), ('Tony', 'grandfather', 'Clarence')]}]
['son', 'grandfather']