code: public boolean checkInstanceOf(Context context, CharSequence targetClassName,
              CharSequence loaderPackage, Class<?> referenceClass) {
          if ((targetClassName == null) || (referenceClass == null)) {
              return false;
          }
  
          final Class<?> targetClass = loadOrGetCachedClass(context, targetClassName, loaderPackage);
          if (targetClass == null) {
              return false;
          }
  
          return referenceClass.isAssignableFrom(targetClass);
      }
docs: Returns whether a target class is an instance of a reference class.
  <p>
  If a class cannot be loaded by the default {@link ClassLoader}, this
  method will attempt to use the loader for the specified app package.
  </p>