Task: Categorize the tweet's emotional tone as either 'neutral or no emotion' or identify the presence of one or more of the given emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust).
Tweet: Harking back to 2012 - DT's challenge to @POTUS...I will give...DT a hearty thank you...if he will release his tax returns....
This tweet contains emotions: 
joy