code: function pump(p) {
    if (p.pumping) return;
    p.pumping = true;
    function push() {
      ++totalPushed;
      if (p.push(config.message) !== false) {
        setTimeout(push,0);
      } else {
        p.pumping = false;
      }
    }
    push();
  }
docs: -- pump messages on a producer