Takes a list of SeqRecordExpanded objects corresponding to a gene_code
        and produces the gene_block as string.

        :param block:
        :return: str.

def convert_to_string(self, block):
        """
        Takes a list of SeqRecordExpanded objects corresponding to a gene_code
        and produces the gene_block as string.

        :param block:
        :return: str.
        """
        if self.aminoacids:
            molecule_type = "protein"
        else:
            molecule_type = "dna"

        out = None
        for seq_record in block:
            if not out:
                out = '&[{0}]\n'.format(molecule_type, seq_record.gene_code)
            taxon_id = '{0}_{1}_{2}'.format(seq_record.voucher_code,
                                            seq_record.taxonomy['genus'],
                                            seq_record.taxonomy['species'],
                                            )
            sequence = get_seq(seq_record, self.codon_positions, self.aminoacids,
                               self.degenerate)
            seq = sequence.seq
            if sequence.warning:
                self.warnings.append(sequence.warning)

            out += '{0}{1}\n'.format(taxon_id.ljust(55), seq)
        return out