Ages ago before mobile internet I had printout of a library I wrote, 10 pages in small fonts, to read/review on a long train ride. A couple of days later I acci

Ages ago before mobile internet I had printout of a library I wrote, 10 pages in small fonts, to read/review on a long train ride. A couple of days later I accidentally deleted the file. No backup, no version control. I was able to type in all the code again thanks to the print-out. It will never happen again ... because I never print anything out again.