return strings.ReplaceAll(s, ",", "%2c")
	}

	var b strings.Builder
	written := 0
	for i := 0; i < len(s); i++ {
		if s[i] == ',' {
			filterSrcsetElement(s, written, i, &b)
			b.WriteString(",")
			written = i + 1
		}
	}
	filterSrcsetElement(s, written, len(s), &b)
	return b.String()
}

// Derived from https://play.golang.org/p/Dhmj7FORT5