#!/usr/bin/perl

use strict;
use autodie;
use warnings;
use LaTeX::TOM;
use Data::Dumper::Concise;

my $file = 'input.tex';

open my $fh, '<', $file;

my $parser = LaTeX::TOM->new;
my $tree   = $parser->parseFile($file);
$tree->getNodesByCondition(
    sub {
        my $node = shift;
        $node->getNextGroupNode;
        print Dumper($node);
    }
);