As a complete aside, I much prefer to write logic that does not modify a file “in place.”   Even if I very easily can.   I always want to generate a new copy ... a new “generation,” if you prefer ... of that file.   And then to devise the logic so that it subsequently moves the original file aside and moves the new version into its place ... perhaps adding the old version (properly and meaningfully renamed) to a handy nearby zip-file backup.   This approach both saves ammunition and preserves the structural integrity of my foot ... ;-)