code: public void assertIsInstanceOf(Description description, Object actual, Class<?> type) {
      checkNotNull(type);
      assertNotNull(description, actual);
      if (!type.isInstance(actual)) {
        String format = "expecting <%s> to be an instance of:<%s> but was instance of:<%s>";
        throw failures.failure(description, new BasicErrorMessageFactory(format, actual, type, actual.getClass()));
      }
    }
docs: Asserts that the <em>actual</em> object is an instance of the given type.
  
  @param description the description of the <em>actual</em> object.
  @param actual the <em>actual</em> object.
  @param type the type to check the <em>actual</em> object against.
  @throws NullPointerException if the given type is {@code null}.
  @throws AssertionError if the <em>actual</em> object is {@code null}.
  @throws AssertionError if the <em>actual</em> object is not an instance of the given type.