How to print date-time stamps using UTC ISO

What's the best way to print a date-time stamp in your favorite coding language? So far I have demonstration code in bash, C, C++, Elixir, Go, Java, Python, and Ruby: https://github.com/joelparkerhenderson/demo_date_time_format https://github.com/joelparkerhenderson/demo_date_time_format Feedback and constructive criticism is welcome. Pull requests are welcome. If you know a language and want to add it, please contribute. Thanks!