I thought in Processing the syntax “line( x1, y1, x2, y2)” is a good design. It is very clear that if you type in the coordinates of the start point and the end point then you can get a line.
But after the class presentation I find that this is not that “good”. I know Processing so I think “line(x1, y1, x2, y2)” is clear and simple, but for someone doesn’t know Processing or coordinates, these four figures may be very confusing.