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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 load_variants(manifest_path, database, **kwargs):
    "Variant loading requires only a VCF file and will never load a duplicate."
    manifest = ManifestReader(manifest_path)

    vcf_info = manifest.section('vcf')

    # No data regarding VCF
    if 'file' not in vcf_info:
        return

    cursor = connections[database].cursor()

    vcf_path = os.path.join(os.path.dirname(manifest_path), vcf_info['file'])

    with open(vcf_path) as fin:
        log.debug("opening {0} in {1}".format(vcf_path, __name__))
        stream = VariantStream(fin)
        columns = stream.output_columns
        db_table = Variant._meta.db_table
        pgcopy_batch(stream, db_table, columns, cursor, database)

    VARIANT_CHANNEL.publish(manifest_path=manifest_path, database=database)