// Test basics, prescripts. Notably, the upper and lower prescripts' content need to be
// aligned on the right edge of their bounding boxes, not on the left as in postscripts.
$
attach(upright(O), bl: 8, tl: 16, br: 2, tr: 2-),
attach("Pb", bl: 82, tl: 207) + attach(upright(e), bl: -1, tl: 0) + macron(v)_e \
$