def template_url(url_template: str, state_machine_name: str, label: str) ->str:
    """
    Templates a URL for an external service.

    Adds the label and state machine to a url that contains placeholders in the
    format `<label>` or '<state_machine>'.
    """
    return url_template.replace('<label>', label).replace('<state_machine>',
        state_machine_name)
