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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 variants(ctx, variant_id, chromosome, end_chromosome, start, end, variant_type, sv_type):
 """Display variants in the database."""

    if sv_type:
        variant_type = 'sv'

    adapter = ctx.obj['adapter']

    if (start or end):
        if not (chromosome and start and end):
            LOG.warning("Regions must be specified with chromosome, start and end")
            return

    if variant_id:
        variant = adapter.get_variant({'_id':variant_id})
        if variant:
            click.echo(variant)
        else:
            LOG.info("Variant {0} does not exist in database".format(variant_id))
        return

    if variant_type == 'snv':
        result = adapter.get_variants(
            chromosome=chromosome,
            start=start,
            end=end
        )
    else:
        LOG.info("Search for svs")
        result = adapter.get_sv_variants(
            chromosome=chromosome,
            end_chromosome=end_chromosome,
            sv_type=sv_type,
            pos=start,
            end=end
        )

    i = 0
    for variant in result:
        i += 1
        pp(variant)

    LOG.info("Number of variants found in database: %s", i)