code: def deleteDuplicates(self, head):
      if head is None:
          return None
      pos = head
      while pos is not None and pos.next is not None:
          if pos.val == pos.next.val:
              pos.next = pos.next.next
          else:
              pos = pos.next
      return head
  
label_desc: Use image node_id 1 for calling the Solution obj's underlying member method code with example usage: obj.deleteDuplicates(head) and returns: head, None