my $my_doc = doc {
    html {
        head { title { text "Title" } };
        body {
            p { class_ "warning"; text "paragraph" }
        };
    }
};

use Data::Dumper;
$Data::Dumper::Indent = $Data::Dumper::Terse = 1;
print Dumper $my_doc;
# [
#   'html',
#   undef,
#   [
#     [
#       'head',
#       undef,
#       [
#         [
#           'title',
#           undef,
#           [
#             'Title'
#           ]
#         ]
#       ]
#     ],
#     [
#       'body',
#       undef,
#       [
#         [
#           'p',
#           [
#             [
#               'class',
#               'warning'
#             ]
#           ],
#           [
#             'paragraph'
#           ]
#         ]
#       ]
#     ]
#   ]
# ]