code: public function post($url, $parameters = false, $content_type = false)
      {
          if (! is_object($url)) {
              $url = new SimpleUrl($url);
          }
          if ($this->getUrl()) {
              $url = $url->makeAbsolute($this->getUrl());
          }
  
          return $this->load($url, new SimplePostEncoding($parameters, $content_type));
      }
docs: Fetches the page content with a POST request.
  
  @param string/SimpleUrl $url                Target to fetch as string.
  @param hash/SimpleFormEncoding $parameters  POST parameters or request body.
  @param string $content_type                 MIME Content-Type of the request body
  
  @return string                              Content of page.