def roles(self):
"""An iterator of the game roles.
Yields:
Role: A game role.
"""
with Frame():
role_variable = Term()
role_query_term = self._role_functor(role_variable)
with self._stateless_query(role_query_term) as q:
while q.next_solution():
yield Role._from_atom(role_variable.get_atom())
