How to export shared methods/class in stenciljs?

Hi Team,
I want to publish my shared method in the library which is build by stenciljs then other developer can reuse it.

I research on stencilj website and forum, but not find any topic.
With stackoverflow, i found few similar issue:

After export my util in index.ts, it’s build successfully.

export * from './components';
export * from './components/my-util';

But when importing my-util in other project to reuse it. I got the strange error

import { myUtil } from 'my-library';

Error: Module not found: Error: Package path . is not exported from package ...

Do we have any guideline to export set of shared method/class …?
How can i fix above error?
Thank for help.