docopt.py 文件源码

def printable_usage(doc):
    # in python < 2.7 you can't pass flags=re.IGNORECASE
    usage_split = re.split(r'([Uu][Ss][Aa][Gg][Ee]:)', doc)
    if len(usage_split) < 3:
        raise DocoptLanguageError('"usage:" (case-insensitive) not found.')
    if len(usage_split) > 3:
        raise DocoptLanguageError('More than one "usage:" (case-insensitive).')
    return re.split(r'\n\s*\n', ''.join(usage_split[1:]))[0].strip()