Convert a string to a escaped ASCII representation including quotation marks
    :param s: a string
    :return: ASCII escaped string

def string(s):
    """
    Convert a string to a escaped ASCII representation including quotation marks
    :param s: a string
    :return: ASCII escaped string
    """
    ret = ['"']
    for c in s:
        if ' ' <= c < '\x7f':
            if c == "'" or c == '"' or c == '\\':
                ret.append('\\')
            ret.append(c)
            continue
        elif c <= '\x7f':
            if c in ('\r', '\n', '\t'):
                # unicode-escape produces bytes
                ret.append(c.encode('unicode-escape').decode("ascii"))
                continue
        i = ord(c)
        ret.append('\\u')
        ret.append('%x' % (i >> 12))
        ret.append('%x' % ((i >> 8) & 0x0f))
        ret.append('%x' % ((i >> 4) & 0x0f))
        ret.append('%x' % (i & 0x0f))
    ret.append('"')
    return ''.join(ret)