docs: function kill(req, res) {
    if(!this._busy || !this.ps) return res.send(NotBusy);
    if(this._busy && this._written) return res.send(Unkillable);
    this.ps.removeAllListeners();
    this._busy = false;
    this._written = false;
    function onClose() {
      res.send(null, Constants.OK);
      // re-spawn for next execution
      //this.spawn();
    }
    this.ps.once('close', onClose.bind(this))
    process.kill(this.ps.pid, 'SIGQUIT');
    this.emit('kill');
  }