[John] asked his father [George] to tell him a bedtime story. After thinking for a bit, [George] decided to tell [John] about the time that he had gone fishing with his father [Clarence] when he was a kid.
('John', 'Clarence')
[John] asked his father [George] to tell him a bedtime story. After thinking for a bit, [George] decided to tell [John] about the time that he had gone fishing with his father [Clarence] when he was a kid.
[{('John', 'grandfather', 'Clarence'): [('John', 'father', 'George'), ('George', 'father', 'Clarence')]}]
['father', 'father']