[John] and his grandfather [Clarence] are going mountain climbing. [John]'s brother [Jerry] is too afraid of heights to tag along.
('Jerry', 'Clarence')
[John] and his grandfather [Clarence] are going mountain climbing. [John]'s brother [Jerry] is too afraid of heights to tag along.
[{('Jerry', 'grandfather', 'Clarence'): [('Jerry', 'brother', 'John'), ('John', 'grandfather', 'Clarence')]}]
['brother', 'grandfather']