```js
// .storybook/main.js

module.exports = {
  stories: ['../src/**/*.stories.mdx', '../src/**/*.stories.@(js|jsx|ts|tsx)'],
  addons: [
    '@storybook/addon-links',
    '@storybook/addon-essentials',
    '@storybook/addon-interactions',
  ],
  /* 
   * 👇 The `config` argument contains all the other existing environment variables.
   * Either configured in an `.env` file or configured on the command line.
  */
  env: (config) => ({
    ...config,
    EXAMPLE_VAR: 'An environment variable configured in Storybook',
  }),
};
```