cfunction
src/core/os.c on line 1775, column 1
(os/strftime fmt &opt time local)
Format the given time as a string, or the current time if `time` is
not given. The time is formatted according to the same rules as the
ISO C89 function strftime(). The time is formatted in UTC unless
`local` is truthy, in which case the date is formatted for the
local timezone.