presto-main/src/main/java/io/prestosql/sql/rewrite/ShowStatsRewrite.java/Visitor/createEstimateRepresentation
class Visitor:        private static Expression createEstimateRepresentation(Estimate estimate)
        {
            if (estimate.isUnknown()) {
                return NULL_DOUBLE;
            }
            return new DoubleLiteral(Double.toString(estimate.getValue()));
        }