Function is

src/svg.js:176–189

(o, type)

    return out;
}
function is(o, type) {
    type = Str.prototype.toLowerCase.call(type);
    if (type == "finite") {
        return isFinite(o);
    }
    if (type == "array" &&
        (o instanceof Array || Array.isArray && Array.isArray(o))) {
        return true;
    }
    return  type == "null" && o === null ||
            type == typeof o && o !== null ||
            type == "object" && o === Object(o) ||
            objectToString.call(o).slice(8, -1).toLowerCase() == type;
}
/*\
 * Snap.format
 [ method ]