Rollup over timeseries

select(timeseries(collection1, q=“*:*”, 
                  field="Reported_Date_dt", 
                  start="2018-07-20T00:00:00Z", 
                  end="2018-08-20T23:59:59Z", 
                  gap="+1DAY", 
                  format="YYYY-MM-dd", 
                  sum(a), 
                  sum(b)),
       Reported_Date_dt,
       sum(a) as sumA,
       sum(b) as sumB,
       add(sumA, sumB) as combinedSum)