This class is an abstraction of the AutoML explainer model as
        described in Training Explainers. It has no
        explicit constructor, but rather is obtained by invoking
        Classifier.getExplainer() or
        Regressor.getExplainer().
      
        Explainer exposes a single method,
        explain(), in two variants, both of which are
        described in this section.
Version 1
          This form of explain() is a JavaScript
          wrapper for ML_EXPLAIN_TABLE,
          and explains the training data from a given table using any
          supplied options, and placing the results in an output table.
Signature
- Explainer.explain( Table testData, Table outputTable[, Object options] )
Arguments
- testData(- Table): Table containing data to be explained.
- outputTable(- Table): Table used for storing results.
- options(- Object) (optional): Set of options to use when explaining. For more information, see Table Explanations.
Return type
- None. (Inserts into a table.) 
Version 2
          Explains a sample containing training data, which must contain
          members used in training; extra members are ignored. This form
          of explain() is a wrapper for
          ML_EXPLAIN_ROW.
Signature
- explain( Object sample[, Object options] )
Arguments
- sample(- Object): A sample containing training data.
- options(- Object) (optional): Options to be used; see Row Explanations, for more information.
Return type
- None.