function hugotOverrideFirstNext(func){
  document.hugotOverrideFirstNext = func;
}

document.onkeydown = function (event) {
  switch (event.keyCode) {
    case 37:
      //left key
      document.getElementById('previous').click();
    case 38:
      console.log("Up key is pressed.");
      break;
    case 39:
      //right key
      if (document.hugotOverrideFirstNext) {
        let func = document.hugotOverrideFirstNext;
        document.hugotOverrideFirstNext = null;
        func();
        return;
      }

      document.getElementById('next').click();
      break;
    case 40:
      console.log("Down key is pressed.");
      break;
  }
};