use strict;
use warnings;
use Data::Dump qw/pp dd/;

use Scalar::Util qw/looks_like_number/;
use Devel::Peek;

sub is_string {
    Dump($_[0]);
    warn "$_[0] looks_like_number\n\n\n"
      if looks_like_number($_[0]);
}


is_string(1);
is_string("42");

my $n=1;
my $s="42";


is_string($n);
is_string($s);

$n.="";                                 # cast to string
$s+=0;                                  # cast to num
is_string($n);
is_string($s);