@Override
  public String toString() {
    if (myCallStack.length == 0) {
      return String.valueOf(myOffset);
    }
    StringBuilder s = new StringBuilder();
    for (int offset : myCallStack) {
      if (s.length() != 0) s.append(',');
      s.append(offset);
    }
    return myOffset + "[" + s + "]";
  }
@Override
  public String toString()