docs: function (idx, arrayOrLength) {
          
          if (!Arrays._isNonNegativeInteger(idx))
              throw "IllegalArgumentException: idx must be a non-negative Integer.";
          
          if (Arrays.isArrayLike(arrayOrLength))
              arrayOrLength = arrayOrLength.length;
          
          if (   typeof arrayOrLength === 'number'
              && idx >= arrayOrLength )
              throw "IndexArrayOutOfBoundException: idx must be in the 0-" + (arrayOrLength - 1) + " range.";
      
      }