What does “哪” here mean? I'm reading a children's book called 《绿豆班的那些事儿》. I came across this sentence and don't really understand the significance of the “哪” at the end: "真不愧为绿豆老师的口头禅哪." If anyone could take the time to explain this to me, it'd would be greatly appreciated! Thank you so much for your time!