public boolean isInScope(Namespace ns) {
    if (ns == scope[depth][0]) {
      return true;
    }
    final int ip = binarySearch(scope[depth], 1, scope[depth].length, ns);
    if (ip >= 0) {
      // we have the same prefix.
      return ns == scope[depth][ip];
    }
    return false;
  }
public boolean isInScope(Namespace ns)