Definition: Given a 'poster' sentence and a corresponding 'response' (often, from Facebook or Reddit)classify the sentiment of the given response into four categories: 1) Positive, 2) Negative, 3) Neutral, and 4) Mixed if it contains both positive and negative.
Input: Poster: Happy 71st Birthday, Vice President Joe Biden! I still have one year on ya! #72andStrong  Responser: Gotta laugh. You still have a year on Biden? You anticipating that gap might close someday?!!
