code: func Implementsf(t TestingT, interfaceObject interface{}, object interface{}, msg string, args ...interface{}) bool {
  	if h, ok := t.(tHelper); ok {
  		h.Helper()
  	}
  	return Implements(t, interfaceObject, object, append([]interface{}{msg}, args...)...)
  }
docs: // Implementsf asserts that an object is implemented by the specified interface.
  //
  //    assert.Implementsf(t, (*MyInterface, "error message %s", "formatted")(nil), new(MyObject))