docs: function enhanceSpm (comName, checkSignature, fn) {
    var sp = new SerialPort(comName)
      , open = false;
  
    sp.writable = true;
    sp.on('open', function() {
      open = true;
      if (checkSignature)
        getSignature(sp, function(e, sig) {
          fn(e, sp, sig);
        });
      else
        fn(null, sp, null);
    });
  
    sp.once('error', function(e) {
      console.log('ERROR', e, comName);
      if (!open)
        fn(e);
    });
  }