Task: Categorize the tweet's emotional expression, classifying it as either 'neutral or no emotion' or as one or more of the specified emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that reflect the tweeter's state of mind.
Tweet: @yap_yip --an uncertainty. [Halsey teases, her lips curving into a jovial smirk.]
This tweet contains emotions: 
joy, optimism