[George] was having a cookout one day, and invited his sister [Nancy]. [Nancy]'s brother [Nicholas] drove them to the cookout.
('Nicholas', 'George')
[George] was having a cookout one day, and invited his sister [Nancy]. [Nancy]'s brother [Nicholas] drove them to the cookout.
[{('Nicholas', 'brother', 'George'): [('Nicholas', 'sister', 'Nancy'), ('Nancy', 'brother', 'George')]}]
['sister', 'brother']