title: What is "internal vertical borders" / "internal horizontal borders"?
body: <p>The <a href="https://developers.google.com/apps-script/reference/spreadsheet/range#setbordertop,-left,-bottom,-right,-vertical,-horizontal" rel="nofollow noreferrer">setBorder()</a>
  has <code>vertical</code> and <code>horizontal</code> arguments, what are these exactly?</p>