Task: Determine the prevailing emotional tone of the tweet, categorizing it as either 'neutral or no emotion' or as one or more of the given emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that most accurately represent the tweeter's mental state.
Tweet: One of the great/horrible moments as a professor is seeing a wonderful student leaving your university to pursue his/her true passion.
This tweet contains emotions: 
joy, pessimism, sadness