I'd be very grateful if you could also do some or all of:

 1. extract the inside of this for-loop to a separate function,
 2. gofmt,
 3. adjust the readme to reflect the new format of ico argument.

I will have to do all of this before I close the merge/pull-request, so if you could do that it would make it easier for me to do that sooner. Also I must adjust the licensing mumbo jumbo somehow to include you as coauthor.

Thanks again for your contribution!