Draw an arc inscribed within the rect. ‘color’ is the clut index (scalar or [r g
b] triplet) that you want to poke into each pixel; default produces black with
the standard CLUT for this window’s pixelSize. Default ‘rect’ is entire window.
Angles are measured clockwise from vertical. ‘penWidth’ and ‘penHeight’ are the
width and height of the pen to use. penWidth must equal penHeight and the
‘penMode’ argument is currently ignored.