Task: Identify the primary emotion conveyed in the tweet and assign it to either 'neutral or no emotion' or one or more of the provided emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that best capture 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