or download this
set exire to 3 seconds
one second later CGI::Session=HASH(0xa965fc) / cf27e3ec9ff5a06a5bef449
+1e830c8b6 load
...
two seconds later var=value
two seconds later var=value
three seconds later CGI::Session=HASH(0xa965ec) / cf27e3ec9ff5a06a5be
+f4491e830c8b6 is_expired