#!/usr/bin/perl -w
use strict;
sub pr {
    print "'$_[0]' (no limit) => [".join(",",map { defined $_ ? "'$_'" : 'undef' } split /=/,$_[0])."]\n" ;
    print "'$_[0]' (limit 1) => [".join(",",map { defined $_ ? "'$_'" : 'undef' } split /=/,$_[0],1)."]\n" ;
    print "'$_[0]' (limit 2) => [".join(",",map { defined $_ ? "'$_'" : 'undef' } split /=/,$_[0],2)."]\n" ;
}

pr('');
pr('a');
pr('=');
pr('a=');
pr('a=b');