func AppendQuotedArg(dst, src []byte) []byte {
	for _, c := range src {
		// See http://www.w3.org/TR/html5/forms.html#form-submission-algorithm
		if c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c >= '0' && c <= '9' ||
			c == '*' || c == '-' || c == '.' || c == '_' {
			dst = append(dst, c)
		} else {
			dst = append(dst, '%', hexCharUpper(c>>4), hexCharUpper(c&15))
		}
	}
	return dst
}
func AppendQuotedArg(dst, src []byte) []byte {
	for _, c := range src {
		// See http://www.w3.org/TR/html5/forms.html#form-submission-algorithm
		if c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' || c >= '0' && c <= '9' ||
			c == '*' || c == '-' || c == '.' || c == '_' {
			dst = append(dst, c)
		} else {
			dst = append(dst, '%', hexCharUpper(c>>4), hexCharUpper(c&15))
		}
	}
	return dst
}
// AppendQuotedArg appends url-encoded src to dst and returns appended dst.