[Clarence] took his grandson [Dennis] to the concert. [Dennis]'s father [Nicholas] showed up later on into the concert.
('Nicholas', 'Clarence')
[Clarence] took his grandson [Dennis] to the concert. [Dennis]'s father [Nicholas] showed up later on into the concert.
[{('Nicholas', 'father', 'Clarence'): [('Nicholas', 'son', 'Dennis'), ('Dennis', 'grandfather', 'Clarence')]}]
['son', 'grandfather']