说我有一个聊天会话的以下数据框：
Session Name Content
1 John Hi!
1 John my name is John
1 Sarah Hello John, how can I help?
1 John I need to check my current balance.
1 Sarah I can help you with that.
1 Sarah may I have your account number?
1 Sarah or your SSN?
我想合并所有连续的话语，使数据框看起来像这样：
Session Name Content
1 John Hi! my name is John
1 Sarah Hello John, how can I help?
1 John I need to check my current balance.
1 Sarah I can help you with that. may I have your account number? or your SSN?
我尝试使用groupby创建一个新列，如此处所示适当地标记每行，但没有成功！
Session Name ID Content
1 John 0 Hi!
1 John 0 my name is John
1 Sarah 1 Hello John, how can I help?
1 John 2 need to check my current balance.
1 Sarah 3 I can help you with that.
1 Sarah 3 may I have your account number?
1 Sarah 3 or your SSN?
我还没有找到其他文章来解决类似的问题，但是我可能正在搜索错误的关键字。非常感谢您的投入。