code: def save_snps(self, filename=None):
          
          comment = (
              "# Source(s): {}\n"
              "# Assembly: {}\n"
              "# SNPs: {}\n"
              "# Chromosomes: {}\n".format(
                  self.source, self.assembly, self.snp_count, self.chromosomes_summary
              )
          )
  
          if filename is None:
              filename = self.get_var_name() + "_lineage_" + self.assembly + ".csv"
  
          return lineage.save_df_as_csv(
              self._snps,
              self._output_dir,
              filename,
              comment=comment,
              header=["chromosome", "position", "genotype"],
          )
docs: Save SNPs to file.
  
          Parameters
          ----------
          filename : str
              filename for file to save
  
          Returns
          -------
          str
              path to file in output directory if SNPs were saved, else empty str