#!/usr/bin/perl
$FOO="/etc/passwd";
open FOO || die "Argh: $!\n";

##</code><code>##

nooky:~$ ./foo.pl
Precedence problem: open FOO should be open(FOO) at ./foo.pl line 3.

##</code><code>##

nooky:~$ ./foo.pl
Precedence problem: open FOO should be open(FOO) at ./foo.pl line 3.
Probable precedence problem on logical or at ./foo.pl line 3.