def predict_proba(self, text):
        """Probability estimates.

        The returned estimates for all classes are ordered by the
        label of classes.

        Args:
            text : string, the input text.

        Returns:
            y : array-like, shape = [num_words, num_classes]
            Returns the probability of the word for each class in the model,
        """
        assert isinstance(text, str)

        words = self.tokenizer(text)
        X = self.preprocessor.transform([words])
        y = self.model.predict(X)
        y = y[0]  # reduce batch dimension.

        return y