my %wanted   = ();
    my %hash     = ( 'foo' => [1,2,3], 'bar' =>[3,4,5]);
    $wanted{foo} = delete $hash{foo};

    print "Left-over:\n";
    for $key (keys %hash) {
        print "$key, @{$hash{$key}}\n";
    }

    print "Wanted:\n";
    for $key (keys %wanted) {
        print "$key, @{$wanted{$key}}\n";
    }

##</code><code>##

    Left-over:
    bar, 3 4 5
    Wanted:
    foo, 1 2 3