Return a CSV for each model and dataset.

        Parameters
        ----------
        filename : str or file
            Either the file name (string) or an open file (file-like object)
            where the data will be saved.
        delimiter : str, optional
            Delimiter used in CSV file between fields.
        recommended_only : bool, optional
            If True, only recommended models for each session are included. If
            no model is recommended, then a row with it's ID will be included,
            but all fields will be null.
        include_io :  bool, optional
            If True, then the input/output files from BMDS will also be
            included, specifically the (d) input file and the out file.

        Returns
        -------
        None

def to_csv(self, filename, delimiter=",", recommended_only=False, include_io=True):
        """
        Return a CSV for each model and dataset.

        Parameters
        ----------
        filename : str or file
            Either the file name (string) or an open file (file-like object)
            where the data will be saved.
        delimiter : str, optional
            Delimiter used in CSV file between fields.
        recommended_only : bool, optional
            If True, only recommended models for each session are included. If
            no model is recommended, then a row with it's ID will be included,
            but all fields will be null.
        include_io :  bool, optional
            If True, then the input/output files from BMDS will also be
            included, specifically the (d) input file and the out file.

        Returns
        -------
        None

        """
        df = self.to_df(recommended_only, include_io)
        df.to_csv(filename, index=False, sep=delimiter)