Helper snippet to render the dynamic values from FormIt

fiDynamicFieldsEmail.php

<?php

/**
 * fiDynamicFields snippet
 *
 * the snippet to manipulate this dynamic form, to parse the HTML code and
 * to hold the submitted values if the page goes back to the same page.
 *
 * @link http://www.virtudraft.com/blog/dynamic-fields-in-multiple-pages-for-formit.html
 * @author goldsky <[email protected]>
 * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3
 */

/**
 * &fields=`field_name_1, field_name_2, field_name_3`
 * Name of fields to be captcured
 */
$fields = $modx->getOption('fields', $scriptProperties);
if (empty($fields)) {
    $modx->log(modX::LOG_LEVEL_ERROR, '[fiDynamicFields] is missing &fields');
    return;
}
/**
 * &itemTpl=`a chunk name`
 * Chunk name as template to render each row
 */
$itemTpl = $modx->getOption('itemTpl', $scriptProperties);

/**
 * &wrapperTpl=`a chunk name`
 * (optional)
 * Chunk name to wrap rendered items and place the javascript code.
 * Leave this empty if uneeded.
 */
$wrapperTpl = $modx->getOption('wrapperTpl', $scriptProperties);
if (empty($itemTpl)) {
    $modx->log(modX::LOG_LEVEL_ERROR, '[fiDynamicFields] is missing &itemTpl');
    return;
}
$phsPrefix = $modx->getOption('phsPrefix', $scriptProperties, 'dynfield.');
if (!isset($_POST)) {
    return;
}
$fieldsArray = array_map('trim', @explode(',', $fields));
$assoc = array();

/**
 * You MUST sanitize the submitted data manually in here,
 * because the expected inputs are based on specific cases
 *
 * @link http://php.net/manual/en/function.filter-input-array.php filter_input_array
 */
$data = $_POST;

foreach ($data as $k => $v) {
    if (in_array($k, $fieldsArray)) {
        $assoc[$k] = array();
        if (is_array($v)) {
            foreach($v as $x) {
                $assoc[$k][] = $x;
            }
        } elseif (is_string($v)) {
            $valArray = array_map('trim', @explode(',', $v));
            foreach ($valArray as $x) {
                $assoc[$k][] = $x;
            }
        }
    }
}
$reverting = array();
foreach ($assoc as $k => $v) {
    foreach ($v as $key => $val) {
        $reverting[$key][$phsPrefix . $k] = $val;
    }
}
$items = array();
foreach ($reverting as $phs) {
    $items[] = $modx->getChunk($itemTpl, $phs);
}
if (empty($wrapper)) {
    return @implode("\n", $items);
} else {
    $wrapper = array(
        $phsPrefix . 'items' => @implode("\n", $items),
    );
    $output = $modx->getChunk($wrapperTpl, $wrapper);

    return $output;

}

if (empty($wrapper)) {
    return @implode("\n", $items);
}

Why you check $wrapper?