let localzone =
let t = Unix.time () in
let gt = Unix.gmtime t
and lt = Unix.localtime t in
let min_diff =
lt.Unix.tm_hour * 60 + lt.Unix.tm_min -
(gt.Unix.tm_hour * 60 + gt.Unix.tm_min)
in
let day_diff = lt.Unix.tm_yday - gt.Unix.tm_yday in
if day_diff < -1 || day_diff = 1 then min_diff + 24 * 60
else if day_diff > 1 || day_diff = -1 then min_diff - 24 * 60
else min_diff