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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_contig(self, contig_id, length):
 """ Add a contig line to the header. Arguments: contig_id (str):
 The id of the alternative line length (str):
 A description of the info line """

        contig_line = '##contig=<ID={0},length={1}>'.format(
            contig_id, length
        )
        logger.info("Adding contig line to vcf: {0}".format(contig_line))
        self.parse_meta_data(contig_line)
        return