@classmethod
def write_file(cls, snps=None, filename='', vcf=False, atomic=True, **kwargs):
    """ Save SNPs to file.

        Parameters
        ----------
        snps : SNPs
            SNPs to save to file or write to buffer
        filename : str or buffer
            filename for file to save or buffer to write to
        vcf : bool
            flag to save file as VCF
        atomic : bool
            atomically write output to a file on local filesystem
        **kwargs
            additional parameters to `pandas.DataFrame.to_csv`

        Returns
        -------
        str
            path to file in output directory if SNPs were saved, else empty str
        """
    w = cls(snps=snps, filename=filename, vcf=vcf, atomic=atomic, **kwargs)
    return w()
