int limit = length();
int limit = this.nbits;
  public String toString() {    StringBuffer buffer = new StringBuffer();    boolean needSeparator = false;    buffer.append('{');    int limit = length();    for (int i = 0 ; i < limit ; i++) {      if (get(i)) {	if (needSeparator) {	  buffer.append(", ");	} else {	  needSeparator = true;	}	buffer.append(i);      }    }    buffer.append('}');    return buffer.toString();  }