parameters: (node)
return_statement: return slow
docstring: 获取产生循环的那一段
docstring_summary: 获取产生循环的那一段
docstring_tokens: 获取产生循环的那一段
function: def cycle(node):
      """获取产生循环的那一段"""
      slow, fast = node, node.next
      while slow != fast:
          if fast is None or fast.next is None:
              return None
          slow = slow.next
          fast = fast.next.next
      slow = node
      fast = fast.next
      while slow != fast:
          slow = slow.next
          fast = fast.next
      return slow
function_tokens: def cycle ( node ) : slow , fast = node , node . next while slow != fast : if fast is None or fast . next is None : return None slow = slow . next fast = fast . next . next slow = node fast = fast . next while slow != fast : slow = slow . next fast = fast . next return slow