Implement test case for Highly Imbalanced Multiclass Datasets

[mrowebot]

Feedback on using MACEst included the following:

• Doesn't work well for imbalanced datasets and with high concentration of values close to 0 in Multiclass Classification setting
• Set of possible multiple classifications {0, 1, ..., 10}
• MACEst returned enormous bounds for confidence

Implement a test case for this and apply MACEst, then fix if necessary/provide instructions on set up.