should asfreq return future dates as well?
Suppose I have a daily series ts ending on dec 12th, and that I want to make a monthly series out of it, with ts.asfreq(MonthEnd()).

The last date I will obtain is 2011-11-30, but if I want to use this data to calculate returns I do not want to lose data for December and get a MTD return as last datapoint.
So I was wondering if it makes sense that in this case, ts.asfreq(MonthEnd())[-1] returns NaN with date 2012-12-31, while ts.asfreq(MonthEnd())[-1] returns the value of 2011-12-12 with date 2012-12-31.

Any good reason why this should not be the case?

What do you think?
