code: function startWatcher (entryPoint, callback) {
    if (config.commands.build.dev) {
      // Delete the assets (CSS/etc.) before.
      // They might not be there, but we must ensure that they are properly
      // deleted.
      //
      // This is necessary, otherwise, remaining copied CSS files will have
      // an higher priority than the ones provided by the server (from
      // the `assets/` folder).
      rimraf(path.join(createAndGetBuildFolder(), 'css'), () => {
        installDevelopmentWatcher(entryPoint, callback)
      })
    } else {
      installWatcher(entryPoint, callback)
    }
  }
docs: Start watching files and assets.