[Nicholas] had taken his son [Dennis] to the batting cages to practice for his big game. While watching his son, [Nicholas] could n't help but think about when he used to go to the batting cages with his father [Clarence].
('Clarence', 'Dennis')
[Nicholas] had taken his son [Dennis] to the batting cages to practice for his big game. While watching his son, [Nicholas] could n't help but think about when he used to go to the batting cages with his father [Clarence].
[{('Clarence', 'grandson', 'Dennis'): [('Clarence', 'son', 'Nicholas'), ('Nicholas', 'son', 'Dennis')]}]
['son', 'son']