code: public static boolean isBytecode(InputStream is) throws IOException {
  	if (!is.markSupported()) throw new IOException("can only read input streams that support mark/reset");
  	is.mark(-1);
  	// print(bytes);
  	int first = is.read();
  	int second = is.read();
  	boolean rtn = (first == ICA && second == IFE && is.read() == IBA && is.read() == IBE);
  
  	is.reset();
  	return rtn;
      }
docs: check if given stream is a bytecode stream, if yes remove bytecode mark
  
  @param is
  @return is bytecode stream
  @throws IOException