code: def remove(self, index):
          '''Return new tree with index removed.'''
          newtree = LookupTree()
          newtree.root = _remove_down(self.root, index, 0)
          return newtref remove(self, index):
          '''Return new tree with index removed.'''
          newtree = LookupTree()
          newtree.root = _remove_down(self.root, index, 0)
          return newtree
docs: Return new tree with index removed.