'Evaluates the predictor
Parameters
recommender: The BaseRecommender instance
The recommender instance to be evaluated.
metrics: [None|\'rmse\'|\'f1score\'|\'precision\'|\'recall\'|\'nmae\'|\'mae\']
If metrics is None, all metrics available will be evaluated.
Otherwise it will return the specified metric evaluated.
Returns
Returns scores representing how well the recommender estimated the
preferences match real values.'

def evaluate(self, recommender, metrics=None, **kwargs):

    raise NotImplementedError('cannot    instantiate    Abstract    Base    Class')
