// noinspection ES6ConvertVarToLetConst

/**
 * Cache or memoize data.
 *
 * @example
 *      var vx_cacheador = new ItMemoize();
 *      vx_cacheador.ttlSecondsDefault = 3600; // default is 0 never expire.
 *      function calculateAndMemoize(a, b) {
 *          let k = vx_cacheador.keyMake('calculateAndMemoize', arguments);

/**
 * Determine if v is empty. where empty is: null, false, zero, a blank string, 
 * Object with no keys, Array with 0 length, Set or Map with 0 size
 * Note:  weakMap & weakSet can't be determined if they are empty.
 *
 * @param v
 * @returns {boolean}
 */
function empty(v) {
    if(typeof v === 'undefined' || null === v)