if (r.numPop == 1) {
Forest ret = n.cache().get(r);
if (ret != null) r.reduce(n, n2, n.phase, ret);
else n.cache().put(r, r.reduce(n, n2, n.phase, null));
if (r.numPop == 1) {
Forest ret = n.cache().get(r);
if (ret != null) r.reduce(n, n2, n.phase, ret);
else n.cache().put(r, r.reduce(n, n2, n.phase, null));