docs: def sample_string(self, individual=-1):
          """Returns the VCF entry as it appears in the vcf file"""
          base = str(self)
          extra = self.get_sample_info(individual=individual)
          extra = [':'.join([str(j) for j in i]) for i in zip(*extra.values())]
          return '\t'.join([base, '\t'.join(extra)])