code: func Nil(t TestingT, object interface{}, msgAndArgs ...interface{}) bool {
  	if h, ok := t.(tHelper); ok {
  		h.Helper()
  	}
  	if isNil(object) {
  		return true
  	}
  	return Fail(t, fmt.Sprintf("Expected nil, but got: %#v", object), msgAndArgs...)
  }
docs: // Nil asserts that the specified object is nil.
  //
  //    assert.Nil(t, err)