perl -MMemoize -MMemoize::Expire -MSerializeValues -E " \
     sub f { ('X',int rand 100) }; \
     tie my %subcache => 'Memoize::Expire', NUM_USES => 3; \
     tie my %cache => 'SerializeValues', \%subcache; \
     memoize 'f', LIST_CACHE => [ HASH => \%cache ], \
                  SCALAR_CACHE =>'MERGE' ; \
     for (1..6) { say f() }"