use strict;
use warnings;

sub change_record {
    my ($rec) = @_;
    $rec->{m_username} = uc($rec->{m_username});
}

{
    my $stg_username        = "PerlMonk";
    my $stg_password        = "VeryGoodPassword";
    my @stg_email_addresses = ( "Monk1", "Monk2", "Monk3" );

    my $rec = {
        m_username     => $stg_username,
        m_password     => $stg_password,
        m_emailAddress => \@stg_email_addresses,
    };

    print("username:  $rec->{m_username}\n");
    change_record($rec);
    print("username:  $rec->{m_username}\n");
}