[Arthur] likes it when his mother, [Lois], plays the flute. [Lois] learned this skill from her mother, [Mary].
('Arthur', 'Mary')
[Arthur] likes it when his mother, [Lois], plays the flute. [Lois] learned this skill from her mother, [Mary].
[{('Arthur', 'grandmother', 'Mary'): [('Arthur', 'mother', 'Lois'), ('Lois', 'mother', 'Mary')]}]