def write_altsw(target, altsw):
    """
    Write alternate software release to file.

    :param target: File to write to.
    :type target: file

    :param altsw: Radio software release version, if different.
    :type altsw: str
    """
    if altsw is not None:
        target.write('RADIO SOFTWARE RELEASE: {0}\n'.format(altsw))
