Some keys contain a disambiguation mark:  "Eko~ca" vs "Eko~gr" If so, we save these in an `ambiguous` object for later use
function checkAmbiguous(k) {
    let i = k.indexOf('~');
    if (i !== -1) {
        let stem = k.substring(0, i);
        ambiguous[stem] = true;
        return true;
    }
    return false;
}