rrays: (x_train, y_train) or ktrain.Dataset instance
                            returned from one of the texts_from_* functions
        preproc: a ktrain.text.TextPreprocessor instance.
                 As of v0.8.0, this is required.
        multilabel (bool):  If True, multilabel model will be returned.
                            If false, binary/multiclass model will be returned.
                            If None, multilabel will be inferred from data.
        classification(bool): If True, will buil