# require outside the package so that its functions are 
# NOT imported into the UtilLib namespace, so that other
# libraries can use them.
require mysql_wrapper_lib.pl;

package UtilLib;

use strict;
use warnings;

use Exporter;
our @ISA = qw(Exporter);

our %EXPORT_TAGS = (
    'public_constants' => [ qw(...) ],
   ...
);

sub do_something {
...
}

# etc