Po is also an interjection, considered as an alternative to yes or no. Indicating that you need to know more before answering an expression of an idea or thought. Imagine it as a word that means: "I think I know what you mean, but can you say it in another way so I may more fully understand you".

Trump had less “fleeting interjections” this debate than the first round, and slightly more interruptions. Clinton had slightly less fleeting interjections, and the same amount of interruptions. The moderators, however, were much more active in this debate than in the first. They interjected (usually to let the candidate know they were running out of time) 41 times throughout the 90 minute debate.