code: public function request($key = null, $filter = false)
      {
          if (is_null($key)) {
              return $_REQUEST;
          }
  
          $value = (isset($_REQUEST[$key]) ? $_REQUEST[$key] : null);
  
          return $this->filter($value, $filter);
      }
docs: HTTP REQUEST method. (Post or Get Request)
  
  @param string $key
  @param bool   $filter
  
  @return string|null