[Clarence] watched his son [Wayne] play catch. [Wayne] tossed the ball back and fourth with his brother [Nicholas].
('Clarence', 'Nicholas')
[Clarence] watched his son [Wayne] play catch. [Wayne] tossed the ball back and fourth with his brother [Nicholas].
[{('Clarence', 'son', 'Nicholas'): [('Clarence', 'son', 'Wayne'), ('Wayne', 'brother', 'Nicholas')]}]
['son', 'brother']