Would it be possible to add a point at the end of the line?

[andreimoment]

Would it be possible to add a point/dot at the end of the line? Ideally the color and size would be customizable.

See https://www.edwardtufte.com/bboard/q-and-a-fetch-msg?msg_id=0001OR for the usefulness of this feature (you may have to scroll down the page)

An additional option could be having the point appear not at the end of the line but at the highest or lowest value.