code: function instanceOf(instance, target) {
          if (!isFunction(target)) {
              return false;
          }
  
          if (instance instanceof target) {
              return true;
          }
  
          if (instance && instance.$static && instance.$static[$class] && target && target[$interface]) {
              return instanceOfInterface(instance, target);
          }
  
          return false;
      }
docs: Custom instanceOf that also works on interfaces.
  
  @param {Object}   instance The instance to be checked
  @param {Function} target   The target
  
  @return {Boolean} True if it is a valid instance of target, false otherwise