Function addpL

docs/app/js/sanddance-app.js:122080–122080

(x20, y19)

const py = (x18, y17)=>mb * x18 + md * y17;
const addp = (x19, y18)=>add(px(x19, y18), py(x19, y18));
const addpL = (x20, y19)=>addL(px(x20, y19), py(x20, y19));
function boundContext(_, deg) {
    bounds = _;
    if (deg) {