Copyright also applies to the structure of the code. So rewriting it line by line would not be enough to remove all of the GPL-licensed elements. You would also

Copyright also applies to the structure of the code. So rewriting it line by line would not be enough to remove all of the GPL-licensed elements. You would also need to restructure and reorganise it. https://en.wikipedia.org/wiki/Structure,_sequence_and_organization https://en.wikipedia.org/wiki/Structure,_sequence_and_organi...