Function apply

src/SpannedString.test.ts:7–17

(string: SpannedString<string>)

}

function apply(string: SpannedString<string>) {
    return Array.from(string.iterSubstrings())
        .map(([substring, tags]) => {
            let s = substring;
            for (const tag of tags) {
                s = `<${tag}>${s}</${tag}>`;
            }
            return s;
        })
        .join('');
}

function format(string: string, spans: [number, number, string][]) {
    const s = S().appendString(string);