presto-main/src/main/java/io/prestosql/operator/aggregation/ChecksumAggregationFunction.java/ChecksumAggregationFunction/output
class ChecksumAggregationFunction:    public static void output(NullableLongState state, BlockBuilder out)
    {
        if (state.isNull()) {
            out.appendNull();
        }
        else {
            VARBINARY.writeSlice(out, wrappedLongArray(state.getLong()));
        }
    }