gistfile1.txt

In toolbox.js:
let Telemetry = require("devtools/shared/telemetry");

And in telemetry.js:
this.Telemetry = function Telemetry() {
  this.logOncePerBrowserVersion = this.logOncePerBrowserVersion.bind(this);
  this.logEvent                 = this.logEvent.bind(this);
  this.logId                    = this.logId.bind(this);
  this.log                      = this.log.bind(this);
};

module.exports = Telemetry;

Telemetry.prototype = {
....