index.js

var os = require('os')

module.exports = Franz =>
  class Gmail extends Franz {
    overrideUserAgent() {
      if (os.platform() == 'linux')
        return "Mozilla/5.0 (X11; Linux x86_64; rv:72.0) Gecko/20100101 Firefox/72.0"
      else
        return "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36";
    }
  };