index, wid, ok := parseArgNumber(format[i:])
	if ok && 0 <= index && index < numArgs {
		return index, i + wid, true
	}
	p.goodArgNum = false
	return argNum, i + wid, ok
}

func (p *pp) badArgNum(verb rune) {
	p.buf.writeString(percentBangString)
	p.buf.writeRune(verb)
	p.buf.writeString(badIndexString)
}

func (p *pp) missingArg(verb rune) {
	p.buf.writeString(percentBangString)