islset = self._toislset(self.polyhedra, self.symbols)
# the trick is to walk symbols in reverse order, to avoid index updates
for index, symbol in reversed(list(enumerate(self.symbols))):
islset = self._toislset(self.polyhedra, self.symbols)
# the trick is to walk symbols in reverse order, to avoid index updates
for index, symbol in reversed(list(enumerate(self.symbols))):