code: function sassLoaderOptions(options) {
    const DefaultSassLoaderOptions = {
      sourceMap: true
    }
    
    return {
      loader: 'sass-loader',
      options: Object.assign({}, DefaultSassLoaderOptions, options, {
        data: `$env: ${options.env};`
      })
    }
  }
docs: SassLoader
  
  option.data: String? = null
  option.includePaths: Array<String> = []
  option.sourceMap: (Boolean|String)? = undefined
  
  @link [sass-loader](https://github.com/jtangelder/sass-loader)
  @link [node-sass](https://github.com/sass/node-sass)
  @link [getting started with css sourcemaps](https://medium.com/@toolmantim/getting-started-with-css-sourcemaps-and-in-browser-sass-editing-b4daab987fb0)