public void isAssignableTo(Class<?> clazz) {
    if (!clazz.isAssignableFrom(checkNotNull(actual))) {
      failWithActual("expected to be assignable to", clazz.getName());
    }
  }
@Test
  public void testIsAssignableTo_parent() {
    assertThat(String.class).isAssignableTo(Object.class);
    assertThat(NullPointerException.class).isAssignableTo(Exception.class);
  }