node(
                func=split_data,
                inputs=["model_input_table", "params:model_options"],
                outputs=["X_train", "X_test", "y_train", "y_test"],
                name="split_data_node",
            )

I have a question here: here 'model_input_table' is a data frame from data catalog, while how can I know this is not a string?