presto-main/src/main/java/io/prestosql/cost/ComparisonStatsCalculator.java/ComparisonStatsCalculator/estimateExpressionEqualToLiteral
class ComparisonStatsCalculator:    private static PlanNodeStatsEstimate estimateExpressionEqualToLiteral(
            PlanNodeStatsEstimate inputStatistics,
            SymbolStatsEstimate expressionStatistics,
            Optional<Symbol> expressionSymbol,
            OptionalDouble literalValue)
    {
        StatisticRange filterRange;
        if (literalValue.isPresent()) {
            filterRange = new StatisticRange(literalValue.getAsDouble(), literalValue.getAsDouble(), 1);
        }
        else {
            filterRange = new StatisticRange(NEGATIVE_INFINITY, POSITIVE_INFINITY, 1);
        }
        return estimateFilterRange(inputStatistics, expressionStatistics, expressionSymbol, filterRange);
    }