Default setter for undefined return

default_setter.pl

#!/usr/bin/env perl

use v5.14;
use warnings;

# develop mode
use Smart::Comments;
use Data::Printer;


sub some_function{
	return shift == 1 ? 1 : undef;
}

foreach(0..1){
	my $value = some_function($_);
	$value //= 'default_value';   
	p($value);
}