seq
for Date class arguments.refvalIdxByDate(t0, b, w, epochStr, epochs)
"1 month"
, "1 week"
or "1 day"
t0
go i, i= 1,...,b
years back in time.
For each year, go w
epochs back and include from here to
w
epochs after t0
.
In case of weeks we always go back to the closest monday of this
date. In case of months we also go back in time to closest 1st of
month.