let date_iso8601 ?(tz=true) timestamp =
let tm = Unix.gmtime timestamp in
let res =
Printf.sprintf
"%04d-%02d-%02dT%02d:%02d:%02d"
(1900 + tm.Unix.tm_year)
(1 + tm.Unix.tm_mon)
tm.Unix.tm_mday
tm.Unix.tm_hour
tm.Unix.tm_min
tm.Unix.tm_sec
in
if tz then
res ^ "+00:00"
else
res