text: // plusStream: -------(+1)----------(+1)------------>
  
  // minusStream: ----(-1)-------(-1)--------(-1)---->
  
  let plusStream = Bacon.fromEvent($("#plus"), "click").map(1);
  let minusStream = Bacon.fromEvent($("#minus"), "click").map(-1);
  
  let counterStream = plusStream.merge(minusStream).scan(0, (prev, curr) => {
    return prev + curr;
  });
  
  counterStream.assign($("#count"), "text");
  