'Try to find out what commandline to use to invoke asciidoc.'

def _get_asciidoc_cmd(self):

    if (self._args.asciidoc is not None):
        return self._args.asciidoc
    try:
        subprocess.call(['asciidoc'], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
    except OSError:
        pass
    else:
        return ['asciidoc']
    try:
        subprocess.call(['asciidoc.py'], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
    except OSError:
        pass
    else:
        return ['asciidoc.py']
    raise FileNotFoundError
