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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def get_log_format(server=_DEFAULT_SERVER):
    '''
    Get the active log format for the SMTP virtual server.

    :param str server: The SMTP server name.

    :return: A string of the log format name.
    :rtype: str

    CLI Example:

    .. code-block:: bash

        salt '*' win_smtp_server.get_log_format
    '''
    log_format_types = get_log_format_types()
    format_id = _get_wmi_setting('IIsSmtpServerSetting', 'LogPluginClsid', server)

    # Since IIsSmtpServerSetting stores the log type as an id, we need
    # to get the mapping from IISLogModuleSetting and extract the name.
    for key in log_format_types:
        if six.text_type(format_id) == log_format_types[key]:
            return key
    _LOG.warning('Unable to determine log format.')
    return None