hb_set_symmetric_difference (hb_set_t       *set,
			     const hb_set_t *other)
{
  /* Immutible-safe. */
  set->symmetric_difference (*other);
}
hb_set_symmetric_difference (hb_set_t       *set,
			     const hb_set_t *other)
{
   
  set->symmetric_difference (*other);
}