code: public function fetch(string $key, $default = null)
      {
          $val = $this->bag[$key] ?? $default;
          if (!is_array($val)) {
              return trim($val);
          } else {
              return $val;
          }
      }
docs: Get value by parameter name.
  
  @param string $key
  @param mixed|null $default The default value if parameter does not exist
  @return mixed|null