+ def _iter2(self, other):
+ if self.symbols != other.symbols:
+ raise ValueError('arguments must belong to the same space')
+ coordinates1 = self._coordinates.values()
+ coordinates2 = other._coordinates.values()
+ yield from zip(self.symbols, coordinates1, coordinates2)
+
+ def _map2(self, other, func):
+ for symbol, coordinate1, coordinate2 in self._iter2(other):
+ yield symbol, func(coordinate1, coordinate2)