Returns Mac version as a tuple of integers, making it easy to do proper
    version comparisons. On non-Macs, it returns an empty tuple.

def _mac_ver():
    """
    Returns Mac version as a tuple of integers, making it easy to do proper
    version comparisons. On non-Macs, it returns an empty tuple.
    """
    import platform
    import sys
    if sys.platform == 'darwin':
        ver_str = platform.mac_ver()[0]
        return tuple([int(v) for v in ver_str.split('.')])
    else:
        return ()