presto-main/src/main/java/io/prestosql/operator/aggregation/DoubleSumAggregation.java/DoubleSumAggregation/sum
class DoubleSumAggregation:    @InputFunction
    public static void sum(@AggregationState LongDoubleState state, @SqlType(StandardTypes.DOUBLE) double value)
    {
        state.setFirst(state.getFirst() + 1);
        state.setSecond(state.getSecond() + value);
    }