use strict;
use warnings;

sub f {
        $_[0] = $_[0] . '_modified'
}

my $x = 'value';

print 'Here is the modified value ', f($x), '.  Print is a list, eh?', "\n\n";
__END__

jptxs:/home/jptxs $ perl functionPrint
Here is the modified value value_modified.  Print is a list, eh?

jptxs:/home/jptxs $