Includes_Snippet.php

<?php
// &file=`assets/foo/bar.php` indicates the file to include
// &return=`1` return explicit content from return statement in included file
//  default behavior is to use output buffering to capture the content from the include

$output = '';
if (isset($file) && file_exists($modx->config['base_path'] . $file)) {
   if (!isset($return) || $return == false) {
       ob_start();
       include ($modx->config['base_path'] . $file);
       $output = ob_get_contents();
       ob_end_clean();
   } else {
       $output = include ($modx->config['base_path'] . $file);
   }
} else {
  $path_parts = pathinfo($file);
  return sprintf('The file: %s was not found', $path_parts['basename']);
}
return $output;
?>