[Clarence] took his son [Dale] out to dinner to celebrate his promotion. [Dale] brought his son, [Tony], along to celebrate.
('Clarence', 'Tony')
[Clarence] took his son [Dale] out to dinner to celebrate his promotion. [Dale] brought his son, [Tony], along to celebrate.
[{('Clarence', 'grandson', 'Tony'): [('Clarence', 'son', 'Dale'), ('Dale', 'son', 'Tony')]}]
['son', 'son']