code: function (master, other, fnEqual) {
          
          if (!Arrays.isArrayLike(master))
              throw "TypeMismatch: master: Array";
          
          if (!Arrays.isArrayLike(other))
              throw "TypeMismatch: other: Array";
          
          var missing = [];
          
          for (var i = 0, len = master.length; i < len; i++) {
              
              var item = master[i];
              
              if (Arrays.indexOf(item, other, null, fnEqual) < 0)
                  missing.push(item);
          }
          
          return missing;
      }
docs: Returns a list of items found in <code>master</code>
  but not <code>other</code>
  
  @param master {Array}
  @param other {Array}
  @param fnEqual {Function} Optional.
  @return {Array}