This is taken from indexu 7 (categorypage.php)

ob.php

  // this is on top

  ob_start();
  
  
  // this is the content
  
  ..
  ..
  ..


  // this is in the bottom

  if ($lep->config['enable_page_caching']) {      // if cache setting is enabled, read from cache
    etc_cache_build('01'); 
    ob_end_clean();
    etc_cache_read('01');
  }
  else {                                          // else just output the content without cache
    ob_end_flush();
  }



///////////////// cache function, in /etc_function.php

  function etc_cache_build($page_code) {
    global $lep;
    
    if ($page_code=='00') {
      $naming = "/index.php";
    }
    elseif ($page_code=='01') {
      $naming = "/".$lep->input['id'].".php";
    }
    elseif ($page_code=='02') {
      $naming = "/".$lep->input['id'].".php";
    }
    
    $cache_dir = PATH . 'cache/pages/';
    
    if (!is_dir($cache_dir)) {
      mkdir(substr($cache_dir,0,strlen($cache_dir)-1), 0777);
    }

    if (!is_dir($cache_dir.$page_code)) {
      mkdir($cache_dir.$page_code, 0777);
    }
    
    $cache_file = $cache_dir . $page_code . $naming;
    
    $footprint = "\n\n<!-- indexu page cache : ".date('d M Y - H:i:s')." -->";

    $fp = fopen($cache_file, 'w+');
    fwrite($fp, ob_get_contents().$footprint);
    fclose($fp);
  } 


  function etc_cache_read($page_code) {
    global $lep;
    
    $duration = 0;
    
    if ($lep->config['page_caching_duration_base']=='minute') {
      $duration = 60;
    }
    elseif ($lep->config['page_caching_duration_base']=='hour') {
      $duration = 60 * 60;
    }
    elseif ($lep->config['page_caching_duration_base']=='day') {
      $duration = 60 * 60 * 24;
    }
    
    if ($page_code=='00') {
      $naming = "/index.php";
      $cache_timeout = $lep->config['page_caching_index_timeout'] * $duration; 
    }
    elseif ($page_code=='01') {
      $naming = "/".$lep->input['id'].".php";
      $cache_timeout = $lep->config['page_caching_category_timeout'] * $duration; 
    }
    elseif ($page_code=='02') {
      $naming = "/".$lep->input['id'].".php";
      $cache_timeout = $lep->config['page_caching_detail_timeout'] * $duration;
    }
    
    $cache_dir = PATH . 'cache/pages/';
    $cache_file = $cache_dir . $page_code . $naming;
    
    if (file_exists($cache_file) && time() - $cache_timeout < filemtime($cache_file)) {
      include $cache_file;
      etc_runtime();
      exit;
    }
        
  }