code: public function getScriptFile()
      {
          if (isset($this->_scriptFile)) {
              return $this->_scriptFile;
          }
  
          if (isset($_SERVER['SCRIPT_FILENAME'])) {
              return $_SERVER['SCRIPT_FILENAME'];
          }
  
          throw new InvalidConfigException('Unable to determine the entry script file path.');
      }
docs: Returns the entry script file path.
  The default implementation will simply return `$_SERVER['SCRIPT_FILENAME']`.
  @return string the entry script file path
  @throws InvalidConfigException