How to use the planemo.io.warn function in planemo

):
    num_tests = test_results.num_tests
    num_problems = test_results.num_problems

    if num_tests == 0:
        warn(NO_TESTS_MESSAGE)
        return

    if num_problems == 0:
        info(ALL_TESTS_PASSED_MESSAGE % num_tests)

    if num_problems:
        html_report_file = test_results.output_html_path
        message_args = (num_problems, num_tests, html_report_file)
        message = PROBLEM_COUNT_MESSAGE % message_args
        warn(message)

    for testcase_el in test_results.xunit_testcase_elements:
        structured_data_tests = test_results.structured_data_tests
        __summarize_test_case(structured_data_tests, testcase_el, **kwds)

def __handle_summary(
    test_results,
    **kwds
):
    summary_style = kwds.get("summary")
    if summary_style == "none":
        return

    if test_results.has_details:
        __summarize_tests_full(
            test_results,
            **kwds
        )
    else:
        if test_results.exit_code:
            warn(GENERIC_PROBLEMS_MESSAGE % test_results.output_html_path)
        else:
            info(GENERIC_TESTS_PASSED_MESSAGE)

def __summarize_tests_full(
    test_results,
    **kwds
):
    num_tests = test_results.num_tests
    num_problems = test_results.num_problems

    if num_tests == 0:
        warn(NO_TESTS_MESSAGE)
        return

    if num_problems == 0:
        info(ALL_TESTS_PASSED_MESSAGE % num_tests)

    if num_problems:
        html_report_file = test_results.output_html_path
        message_args = (num_problems, num_tests, html_report_file)
        message = PROBLEM_COUNT_MESSAGE % message_args
        warn(message)

    for testcase_el in test_results.xunit_testcase_elements:
        structured_data_tests = test_results.structured_data_tests
        __summarize_test_case(structured_data_tests, testcase_el, **kwds)

\b
        % planemo run cat1-tool.cwl cat-job.json
    """
    path = uri_to_path(ctx, uri)
    # TODO: convert UI to runnable and do a better test of cwl.
    is_cwl = path.endswith(".cwl")
    kwds["cwl"] = is_cwl
    if kwds.get("engine", None) is None:
        kwds["engine"] = "galaxy" if not is_cwl else "cwltool"

    with engine_context(ctx, **kwds) as engine:
        run_result = engine.run(path, job_path)

    if not run_result.was_successful:
        warn("Run failed [%s]" % unicodify(run_result))
        ctx.exit(1)

    outputs_dict = run_result.outputs_dict
    print(outputs_dict)
    output_json = kwds.get("output_json", None)
    if output_json:
        with open(output_json, "w") as f:
            json.dump(outputs_dict, f)

    return 0

def cli(ctx, **kwds):
    """Download and install conda.

    This will download conda for managing dependencies for your platform
    using the appropriate Miniconda installer.

    By running this command, you are agreeing to the terms of the conda
    license a 3-clause BSD 3 license. Please review full license at
    http://docs.continuum.io/anaconda/eula.

    Planemo will print a warning and terminate with an exit code of 7
    if Conda is already installed.
    """
    conda_context = build_conda_context(ctx, **kwds)
    if conda_context.is_conda_installed():
        warn(MESSAGE_ERROR_ALREADY_EXISTS % conda_context.conda_exec)
        exit = EXIT_CODE_ALREADY_EXISTS
    else:
        exit = conda_util.install_conda(conda_context=conda_context, force_conda_build=True)
        if exit:
            warn(MESSAGE_ERROR_FAILED % conda_context.conda_exec)
        else:
            info(MESSAGE_INSTALL_OKAY % conda_context.conda_exec)

    ctx.exit(exit)

if kwds.get("check_diff", False):
        is_diff = diff_repo(ctx, realized_repository, **kwds) != 0
        if not is_diff:
            name = realized_repository.name
            info("Repository [%s] not different, skipping upload." % name)
            return 0

    # TODO: support updating repo information if it changes in the config file
    try:
        shed_context.tsi.repositories.update_repository(
            str(repo_id), tar_path, **update_kwds
        )
    except Exception as e:
        if isinstance(e, bioblend.ConnectionError) and e.status_code == 400 and \
                '"No changes to repository."' in e.body:
            warn("Repository %s was not updated because there were no changes" % realized_repository.name)
            return 0
        message = api_exception_to_message(e)
        error("Could not update %s" % realized_repository.name)
        error(message)
        return -1
    info("Repository %s updated successfully." % realized_repository.name)
    return 0