$ cat t15.pl

use strict;
use warnings;

my @usages = qw( Gilligan 23 Thurston 70 Lovey 98 );
my $ask;

sub cookup2 {
    my %usd = @_;                       # Better be even #.
    sub ask_monkey_about {
        my $cst = shift;
        $usd{$cst};
    };
}

sub cookup {
    my %usd = @_;                       # Better be even #.
    return sub {
        my $cst = shift;
        $usd{$cst};
    };
}

$ask = cookup ( @usages );
print $ask->("Lovey") . "\n";
cookup2 ( @usages );
print ask_monkey_about("Lovey") . "\n";