code: function Logger(manager, source) {
          Object.defineProperties(this, {
              "manager" : {
                  value : manager,
                  writable : false,
                  enumerable : true
              },
              "source" : {
                  value : source,
                  writable : false,
                  enumerable : true
              },
              "_timerData" : {
                  value : {},
                  writable : false,
                  enumerable : false
              }
          });
      }
docs: Logger objects are used to create log events. The constructor for Logger objects is
  private (not accessible outside this module). Instead, they are created through the
  LoggerManager.prototype.createLogger method.