code: function subscribeToStream(streamer, flow){
          var func = function(data){
              setTimeout(() => flow._prePush(data, streamer), 0);
          };
  
          streamer.subscribe(func);
          flow.subscribers[streamer.key] = func;
      }
docs: This method subscribes a Flow (IteratorFlow) to a Streamer to listen for data changes
  This method is placed outside the class to prevent external access
  @param streamer the Streamer to subscribe to
  @param flow the IteratorFlow object which will initiate the push