Task: Classify the mental state of the tweeter based on the tweet, determining if it is 'neutral or no emotion' or characterized by any of the provided emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust).
Tweet: Gloriosa Bazigaga on #Rwanda work: 'I lost relatives in genocide but 15 yrs of peacebuilding has given me optimism it's within our power'
This tweet contains emotions: 
optimism