Function toString

docs/app/js/sanddance-app.js:107114–107116

(_)

    return _ == null || _ === "" ? null : parser(_);
}
function toString(_) {
    return _ == null || _ === "" ? null : _ + "";
}
function toSet(_) {
    const s = {}, n = _.length;
    for(let i = 0; i < n; ++i)s[_[i]] = true;