code: int writeBytes(OutputStream out)
          throws IOException
      {
          int length = myBuffer.length - myOffset;
          byte[] bytes = new byte[length];
          System.arraycopy(myBuffer, myOffset, bytes, 0, length);
          out.write(bytes);
          return length;
      }
docs: Copies the current contents of the Ion binary-encoded byte array to a
  specified stream.
  <p>
  This makes an unchecked assumption that {{@link #serialize(IonDatagram)}
  is already called.
  
  @return the number of bytes written into {@code out}
  
  @throws IOException