code: def symmetric_difference(self, other):
          
          # work only on the lowest level
          # TODO: Allow this to be done for regions with different depths.
          if not (self.maxdepth == other.maxdepth): raise AssertionError("Regions must have the same maxdepth")
          self._demote_all()
          opd = set(other.get_demoted())
          self.pixeldict[self.maxdepth].symmetric_difference_update(opd)
          self._renorm()
          return
docs: Combine with another Region by performing the symmetric difference of their pixlists.
  
          Requires both regions to have the same maxdepth.
  
          Parameters
          ----------
          other : :class:`AegeanTools.regions.Region`
              The region to be combined.