Saves to writer.
Saves to writer. Does NOT close the writer
Returns the score for this datum NB: This is not necessarily a probability
Trains a classifier, using only the datums specified in indices indices is useful for bagging
Saves the current model to a file
Trains the classifier on the given dataset spans is useful during cross validation
Trait for regression Adapted from Classifier trait User: mihais, danebell Date: 11/15/17