open-wc/packages/example-vanilla/.storybook/config.js

import { configure } from '@storybook/polymer';
import { setOptions } from '@storybook/addon-options';

setOptions({
  hierarchyRootSeparator: /\|/,
});

const req = require.context('../stories', true, /\.stories\.js$/);
function loadStories() {
  req.keys().forEach(filename => req(filename));
}

configure(loadStories, module);