code: def move_to_end(self, key, last=True):
          '''Move an existing element to the end (or beginning if last==False).
  
          Raises KeyError if the element does not exist.
          When last=True, acts like a fast version of self[key]=self.pop(key).
  
          '''
          link = self.__map[key]
          link_prev = link.prev
          link_next = link.next
          link_prev.next = link_next
          link_next.prev = link_prev
          root = self.__root
          if last:
              last = root.prev
              link.prev = last
              link.next = root
              last.next = root.prev = link
          else:
              first = root.next
              link.prev = root
              link.next = first
              root.next = first.prev = linf move_to_end(self, key, last=True):
          '''Move an existing element to the end (or beginning if last==False).
  
          Raises KeyError if the element does not exist.
          When last=True, acts like a fast version of self[key]=self.pop(key).
  
          '''
          link = self.__map[key]
          link_prev = link.prev
          link_next = link.next
          link_prev.next = link_next
          link_next.prev = link_prev
          root = self.__root
          if last:
              last = root.prev
              link.prev = last
              link.next = root
              last.next = root.prev = link
          else:
              first = root.next
              link.prev = root
              link.next = first
              root.next = first.prev = link
docs: Move an existing element to the end (or beginning if last==False).
  
          Raises KeyError if the element does not exist.
          When last=True, acts like a fast version of self[key]=self.pop(key).