icalendar--convert-tz-offset
icalendar--convert-tz-offset is a compiled Lisp function in `icalendar.el
'.
(icalendar--convert-tz-offset ALIST DST-P)
Return a cons of two strings representing a timezone start.
ALIST is an alist entry from a VTIMEZONE, like STANDARD.
DST-P is non-nil if this is for daylight savings time.
The strings are suitable for assembling into a TZ variable.