if (numBits == 0) return 0L;
  public long readBits(int numBits)    throws IOException  {    checkClosed();    if (numBits < 0 || numBits > 64)      throw new IllegalArgumentException();    if (numBits == 0)      return 0L;    long bits = 0L;        for (int i = 0; i < numBits; i++)      {	bits <<= 1;	bits |= readBit();      }    return bits;  }