def get_default_ssl_version():
    """Get the highest support TLS version, if none is available, return None.

    :rtype: bool|None
    """
    if hasattr(ssl, 'PROTOCOL_TLSv1_2'):
        return ssl.PROTOCOL_TLSv1_2
    elif hasattr(ssl, 'PROTOCOL_TLSv1_1'):
        return ssl.PROTOCOL_TLSv1_1
    elif hasattr(ssl, 'PROTOCOL_TLSv1'):
        return ssl.PROTOCOL_TLSv1
    return None
Get the highest support TLS version, if none is available, return None.

    :rtype: bool|None