in reply to Epoch time conversion in CSV
As others have said, you want to use DateTime, in particular the from_epoch constructor.
But be careful! You say "I'm in the GMT-5 timezone", which shows a fundamental misunderstanding of timezones. That could put you in New York, or it could put you in Lima, which are in different timezones. As I write this, it is 05:50 in New York but it is 04:50 in Lima, because one of them is in "daylight saving" time and the other is on sensible time.
You should always use timezone names, not offsets, and not abbreviations either as abbreviations like CST are ambiguous (is that CST in north America, or in Cuba, or China, or Australia? They differ by up to fifteen and a half hours!). You must use a timezone name like America/Lima to ensure you always get the correct conversion from epoch time to local time.
Finally, if you're writing out a data file in local time, always include the time zone. This will let other people in different time zones use the data correctly, but it will also help you use the data correctly. You won't have to remember whether you wrote that particular file in your local time, UTC, or something else.