// Deux boucles imbriquées

unitsize(.7cm);

int n=10;
for (int i = 0; i <= n; ++i) {
    for (int j = 0; j <= n; ++j) {
        pen p =rgb(i/n,j/n,0);
        filldraw(shift(j,i)*unitsquare,p,.2bp+black);
    }
}