bernhard@bernhard-Aspire-A515-57:/tmp$ cat t2.pl 
use strict;
use warnings;

use Data::Dx;

my @ElementList;
push @ElementList,
        map { $_, 'X' }
        ( 1, 2 );
Dx( \@ElementList );
bernhard@bernhard-Aspire-A515-57:/tmp$ perl t2.pl
#line 10  t2.pl
( \@ElementList ) = [1, "X", 2, "X"]