src/libs/Bus.js
function subscribe(oSubscriber) {
  const oEventsCallbacks = oSubscriber.events;
  if (!oSubscriber || oEventsCallbacks === und) {
    return false;
  }
  iterateObject(oEventsCallbacks, function (oItem, sChannelId) {
    if (oChannels[sChannelId] === und) {
      oChannels[sChannelId] = {};
    }
    _addSubscribers(oItem, sChannelId, oSubscriber);
  });

  return true;
}
function subscribe(oSubscriber) {
  const oEventsCallbacks = oSubscriber.events;
  if (!oSubscriber || oEventsCallbacks === und) {
    return false;
  }
  iterateObject(oEventsCallbacks, function (oItem, sChannelId) {
    if (oChannels[sChannelId] === und) {
      oChannels[sChannelId] = {};
    }
    _addSubscribers(oItem, sChannelId, oSubscriber);
  });

  return true;
}
subscribe method gets the oEventsCallbacks object with all the handlers and add these handlers to the channel.
@param {Object} oSubscriber
@return {Boolean}