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