def _process_timezone(params: dict) -> Optional[str]:
        """Processes input params used at model creation for time zone specification, and returns the time zone.

        Parameters
        ----------
        params
            Dict from parameter `add_encoders` (kwargs) used at model creation. Relevant parameters are:
            * params={'tz': 'CET'}
        """
        if not params:
            return None

        return params.get(TZ_KEYS[0], None)
Processes input params used at model creation for time zone specification, and returns the time zone.

        Parameters
        ----------
        params
            Dict from parameter `add_encoders` (kwargs) used at model creation. Relevant parameters are:
            * params={'tz': 'CET'}
        
darts/dataprocessing/encoders/encoders.py