anchor.diff:  ```
   
   === The CSS main file
  -under the folder app
  -Create an empty CSS file (or SCSS if you prefer) that we will use to add some style in our Elm app
  +
  +In the folder `meteor-elm-app/packages/elm-app/app`, create an empty `main.css` file (or SCSS if you prefer) that we will use later to add some style in our Elm application.
   
   NB: if you use `elm-css` and you don't need a stylesheet, skip this step and remove the line `api.addFiles('dist/elm-app.css', 'client');` in the package.js file
   
  -=== The app entrypoint
  -under the folder app
  -Create an index.ts file under your app folder (take care of the first line if you don't use SCSS but a `main.css` file )
  +=== The Package mainModule
  +
  +In the folder `meteor-elm-app/packages/elm-app/app`, create a file `index.ts` that will *mount* our Elm application and export the `ports`.
  +
  +A simple version could:
  +
  +```ts
  +import './main.scss'
  +const { Elm } = require('./src/Main.elm')
  +
  +export const init = (configuration: any) => {
  +    const app = Elm.Main.init(configuration)
  +    return app.ports
  +}
  +```
  +
  +But because we want to Type thing as much as possible, let's create this `index.ts` like this:
   
   ```ts
   import './main.scss'
  
positive.code: ```
  
  
  === Create a package
  create  folders
  
  ```shell
  mkdir -p packages/elm-app/{app,dist}
  ```
  
  because we will build with parcel and not with meteor, we will create a new file at the root of the meteor-elm-app called `.meteorignore`
  
  ```
  /packages/elm-app/app/**/*
  ```
  
  because we don't want to push the dist and the `elm-stuff` folders on our repository, we will add them in the .gitignore
  ```
  dist
  elm-stuff
  ```
  
  create a file package.js inside this folder:
  ```js
  Package.describe({
      name: 'elm-app',
  
negative.code:     return app.ports
  }
  ```
  
  With this definition, when we will need some flags or some ports, we will add the new stuff in our interface and the client will have to implement them.
  
  NOTE: Take care of the first line if you don't use SCSS but a `main.css` file
  
  === Build with parcel
  But... wait... why do we use Parcel? Why don't we use the Elm make command? Why don't we use the Meteor bundler for css?
  