code: private function checkVersion(array $fields)
  	{
  		if ( false === $fields['version'] || $fields['version'] !== $this->getVersion() )
  		{
  			throw new ApiException(Errors::ERRCODE_VERSION_WRONG);
  		}
  	}
docs: Check version
  @internal: called by checkFields function
  
  @param array $fields
  @throw ApiException