def _update_pbar(self, pbar_num=1, pbar_msg=None):
        """Update self._pbar and error message during pipeline evaluation.

        Parameters
        ----------
        pbar_num: int
            How many pipelines has been processed
        pbar_msg: None or string
            Error message

        Returns
        -------
        None
        """
        if not isinstance(self._pbar, type(None)):
            if self.verbosity > 2 and pbar_msg is not None:
                self._pbar.write(pbar_msg, file=self._file)
            if not self._pbar.disable:
                self._pbar.update(pbar_num)
Update self._pbar and error message during pipeline evaluation.

        Parameters
        ----------
        pbar_num: int
            How many pipelines has been processed
        pbar_msg: None or string
            Error message

        Returns
        -------
        None