public void finishWrite(OutputStream os) throws Exception {	   	
    	os.write(IMAGE_TRAILER);
		os.close();    	
	}
This is intended to be called after writing all the frames if we write
an animated GIF frame by frame.

@param os OutputStream for the animated GIF
@throws Exception
subs/gif-revert/src/main/java/com/engineer/gif/revert/lib/AnimatedGIFWriter.java