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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 query_locus(self, filter_column, filter_value, feature):
 """ Query for unique locus, raises error if missing or more than one locus in the database. Parameters filter_column : str Name of column to filter results by. filter_value : str Only return loci which have this value in the their filter_column. feature : str Feature names such as 'transcript', 'gene', and 'exon' Returns single Locus object. """

        loci = self.query_loci(
            filter_column=filter_column,
            filter_value=filter_value,
            feature=feature)

        if len(loci) == 0:
            raise ValueError("Couldn't find locus for %s with %s = %s" % (
                feature, filter_column, filter_value))
        elif len(loci) > 1:
            raise ValueError("Too many loci for %s with %s = %s: %s" % (
                feature, filter_column, filter_value, loci))
        return loci[0]