code: def unlink(self):
          '''Remove this node and link any head or tail.'''
          old_head = self.head
          old_tail = self.tail
  
          self.head = None
          self.tail = None
  
          if old_head:
              old_head.tail = old_tail
  
          if old_tail:
              old_tail.head = old_heaf unlink(self):
          '''Remove this node and link any head or tail.'''
          old_head = self.head
          old_tail = self.tail
  
          self.head = None
          self.tail = None
  
          if old_head:
              old_head.tail = old_tail
  
          if old_tail:
              old_tail.head = old_head
docs: Remove this node and link any head or tail.