Done with: ack '2017+' -l | xargs sed -i -e 's/2017+/2018+/g' Checked manually with: git add -p Hello to future James from 2019, and Happy Hacking!
It's up to the end user to decide who is writing and/or overwriting them. It could also be useful to reimplement (refactor) some of the existing World API's to be implemented in terms of these primitives.