[George] was playing catch with his son, [John]. [April] imitated her brother throwing the ball back and forth.
('April', 'George')
[George] was playing catch with his son, [John]. [April] imitated her brother throwing the ball back and forth.
[{('April', 'father', 'George'): [('April', 'brother', 'John'), ('John', 'father', 'George')]}]
['brother', 'father']