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