Forest old = holder[pos];
holder[pos] = parent.pending();
if (pos==0) {
System.arraycopy(holder, 0, position.holder, 0, holder.length);
for(int i=0; i<position.pos; i++) if (position.holder[i]==null) throw new Error("realbad");
Forest rex = position.rewrite(target.getLocation());
Forest old = holder[pos];
holder[pos] = parent.pending();
if (pos==0) {
System.arraycopy(holder, 0, position.holder, 0, holder.length);
for(int i=0; i<position.pos; i++) if (position.holder[i]==null) throw new Error("realbad");
Forest rex = position.rewrite(target.getLocation());