bernhard@bernhard-Aspire-A515-57:/tmp$ cat t1.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 t.pl
Backslash found where operator expected at t.pl line 10, near "Dx \"
        (Do you need to predeclare Dx?)
syntax error at t.pl line 9, near "( "
Execution of t.pl aborted due to compilation errors.
bernhard@bernhard-Aspire-A515-57:/tmp$