code: def share_settings(self, other, keylist=None, include_callbacks=True,
                         callback=True):
          
          if keylist is None:
              keylist = self.group.keys()
          if include_callbacks:
              for key in keylist:
                  oset, mset = other.group[key], self.group[key]
                  other.group[key] = mset
                  oset.merge_callbacks_to(mset)
          if callback:
              # make callbacks only after all items are set in the group
              # TODO: only make callbacks for values that changed?
              for key in keylist:
                  other.group[key].make_callback('set', other.group[key].value)
docs: Sharing settings with `other`