private void writeHeader(OutputStream os, boolean newFormat) throws IOException {
		// 6 bytes: GIF signature (always "GIF") plus GIF version ("87a" or "89a")
		if(newFormat)
			os.write("GIF89a".getBytes());
		else
			os.write("GIF87a".getBytes());			
	}
Write out a zero length data sub-block
subs/gif-revert/src/main/java/com/engineer/gif/revert/lib/AnimatedGIFWriter.java