docs: function uglifyJs(js) {
    // UglifyJS.minify() can only write source maps to the filesystem. Ick.
    // We have to break it down into steps instead.
    //
    // This is all from README.md
  
    const UglifyJS = require('uglify-es')
    const uglified = UglifyJS.minify({ "ignored.js": js.javascript.toString('utf-8') }, {
      sourceMap: {
        content: js.sourceMap,
      },
      compress: {
        unused: false, // apparently it's slow: http://stackoverflow.com/questions/15447727/how-to-speed-up-the-minification-process-of-uglifyjs-2
      }
    })
  
    if (uglified.error) throw uglified.error
  
    return {
      javascript: Buffer.from(uglified.code),
      sourceMap: JSON.parse(uglified.map),
    }
  }