34;train labels should not be in sparse format&#34;)

            for x in x_train:
                features.update(x)
            # max_features = len(features)
            if max_features is None:
                max_features = max(features) + 1
                U.vprint(&#34;max_features is %s&#34; % (max_features), verbose=verbose)
        maxlen = U.shape_from_data(train_data)[1]
        U.vprint(&#34;maxlen is %s&#34; % (maxlen), verbose=verbose)

    # return appropriate model
    if name in [LOGREG, 