$ cat pm_1185726_heredoc_pod.pl
my $str = <<=cut;

=head2 Some documentation

=cut
$ 

##</code><code>##

$ perl -MO=Deparse pm_1185726_heredoc_pod.pl
Use of bare << to mean <<"" is deprecated. Its use will be fatal in Perl 5.28 at pm_1185726_heredoc_pod.pl line 1.
Can't modify scalar in scalar assignment at pm_1185726_heredoc_pod.pl line 1, near "cut;"
pm_1185726_heredoc_pod.pl had compilation errors.
my $str = "" = 'cut';
$ 

##</code><code>##

$ perl -MO=Deparse pm_1185726_heredoc_pod.pl
my $str = "\n=head2 Some documentation\n\n";
pm_1185726_heredoc_pod.pl syntax OK

##</code><code>##

$ cat pm_1185726_heredoc_pod.pl
our $VERSION = '1.234';

my $str = <<"=cut";

=head2 Some documentation

Doco for version: $VERSION

=cut

print $str;

##</code><code>##

$ perldoc pm_1185726_heredoc_pod.pl

##</code><code>##

$ perl -wMstrict pm_1185726_heredoc_pod.pl

=head2 Some documentation

Doco for version: 1.234