Task: Assess the emotional content of the tweet and classify 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 best represent the tweeter's mental state.
Tweet: Happy birthday to Stephen King, a man responsible for some of the best horror of the past 40 years... and a whole bunch of the worst.
This tweet contains emotions: 
joy