SHOW function makes visible some levels of the stack which were previously hidden by a call to
The levels made visible are the ones closest to the top of the stack. Depending on the
levels parameter to the call to
SHOW, the revealed levels could be the whole stack (
levels == 0), a maximum number of levels (
levels >= 0) or a number of levels such that there are at most a certain number ((abs(
levels < 0) of visible levels after the call.
When called with
NULL as parameter,
SHOW wil reveal all levels currently hidden.