Use an empty file called, say ruby-marker to indicate that all of the xml files have been processed. Its modification time can be compared to those of the "x. S" files.
Then use $? To select only the prerequisite "x. S" files that have changed since the last run of the ruby script.
Is the list of prerequisites that are newer than target.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.