code: func NotContainsf(t TestingT, s interface{}, contains interface{}, msg string, args ...interface{}) {
  	if h, ok := t.(tHelper); ok {
  		h.Helper()
  	}
  	if assert.NotContainsf(t, s, contains, msg, args...) {
  		return
  	}
  	t.FailNow()
  }
docs: // NotContainsf asserts that the specified string, list(array, slice...) or map does NOT contain the
  // specified substring or element.
  //
  //    assert.NotContainsf(t, "Hello World", "Earth", "error message %s", "formatted")
  //    assert.NotContainsf(t, ["Hello", "World"], "Earth", "error message %s", "formatted")
  //    assert.NotContainsf(t, {"Hello": "World"}, "Earth", "error message %s", "formatted")