[Jeff] invited his brothers [Robert] and [Kevin] over for dinner one day and they had a good time.
('Kevin', 'Robert')
[Jeff] invited his brothers [Robert] and [Kevin] over for dinner one day and they had a good time.
[{('Kevin', 'brother', 'Robert'): [('Kevin', 'brother', 'Jeff'), ('Jeff', 'brother', 'Robert')]}]
['brother', 'brother']