#!/usr/bin/perl -w
use strict;

my %commas = (
    'notalot'               => 1,
    'england,rugby'         => 1,
    'chicken,egg,duck,feet' => 1,

    ',southampton'          => 0,
    'bristol,'              => 0,
    'iran,,canada,france'   => 0,
);

foreach my $key (keys %commas)
{
    unless (($key =~ /^,|,,|,$/))
    {
        print "PASS";
    }
    else
    {
        print "FAIL";
    }
    print  ": $key\n";
}

##</code><code>##

FAIL: bristol,
PASS: notalot
PASS: england,rugby
FAIL: iran,,canada,france
PASS: chicken,egg,duck,feet
FAIL: ,southampton