def METHOD_NAME(event, channel=None, username=None, api_url=None, hook=None):
    """
    Send an event to a Mattermost channel.
    :param channel:     The channel name, either will work.
    :param username:    The username of the poster.
    :param event:       The event to send to the Mattermost channel.
    :param api_url:     The Mattermost api url, if not specified in the configuration.
    :param hook:        The Mattermost hook, if not specified in the configuration.
    :return:            Boolean if message was sent successfully.
    """
    if not api_url:
        api_url = _get_api_url()
    if not hook:
        hook = _get_hook()
    if not username:
        username = _get_username()
    if not channel:
        channel = _get_channel()
    if not event:
        log.error("message is a required option.")
    log.debug("Event: %s", event)
    log.debug("Event data: %s", event["data"])
    message = "tag: {}\r\n".format(event["tag"])
    for key, value in event["data"].items():
        message += "{}: {}\r\n".format(key, value)
    result = post_message(
        message, channel=channel, username=username, api_url=api_url, hook=hook
    )
    return bool(result)