final int i = at.get(pref);
if(i != -1) return at.val[i];
final Nod n = parent();
return n != null ? n.uri(pref) : null;
}
/**
final int i = at.get(pref);
if(i != -1) return at.val[i];
final Nod n = parent();
if(n != null) return n.uri(pref, ctx);
}
return pref.length == 0 ? ctx.nsElem : null;
}