code: func (r AbsResourceInstance) ContainingResource() AbsResource {
  	return AbsResource{
  		Module:   r.Module,
  		Resource: r.Resource.ContainingResource(),
  	}
  }
docs: // ContainingResource returns the address of the resource that contains the
  // receving resource instance. In other words, it discards the key portion
  // of the address to produce an AbsResource value.