/tmp>cat at.pl
#!/usr/bin/perl

use strict;
use warnings;
use feature 'say';

say '@foo!';
say "\@bar!";
say "@bang!";

/tmp>perl at.pl
Possible unintended interpolation of @bang in string at at.pl line 9.
Global symbol "@bang" requires explicit package name (did you forget to declare "my @bang"?) at at.pl line 9.
Execution of at.pl aborted due to compilation errors.

/tmp>