use strict;
use warnings;
use Data::Dump;

{
    my %toys = ( frisbee => 5 );

    dd \%toys;
    play_around(\%toys);
    dd \%toys;
}

sub play_around {
    die "expected one arg"  unless @_ == 1;
    die "expected hash arg" unless ref($_[0]) eq "HASH";
    our %t; local *t = $_[0];
    $t{leggo} = "yes";
}

##</code><code>##

{ frisbee => 5 }
{ frisbee => 5, leggo => "yes" }