union () {
    linear_extrude (10) polygon([[7.0710678118654755,0],[0,7.0710678118654755],[7.0710678118654755,2*7.0710678118654755],[2*7.0710678118654755,7.0710678118654755]]);
    linear_extrude (10) translate (20,0) polygon([[0,0],[10,0],[10,10],[0,10]]);
}