ocument.getElementsByName("showCounterexample")[0].click();
  } else {
    return;
  }
  event.preventDefault();
}, true);

document.addEventListener("DOMContentLoaded", function() {
    document.querySelector('input[name="showCounterexample"]').onchange=
        function (event) {
      filterCounterexample(this.checked);
    };
});
</script>

<form>
    <input type="checkbox" name="showCounterexample" id="showCounterexample" />
    <label for="showCounterexample">
       Show only relevant lines
    </label>
    <input type="checkbox" name="showArrows"
           id="showArrows" style="margin-left: 10px" />
    <label for="showArrows">
       Show control flow arrows
    </label>
</form>