Return a string representing the frequency.
Examples
>>> pd.DateOffset(5).freqstr '<5 * DateOffsets>'
>>> pd.offsets.BusinessHour(2).freqstr '2BH'
>>> pd.offsets.Nano().freqstr 'N'
>>> pd.offsets.Nano(-3).freqstr '-3N'
previous
pandas.tseries.offsets.CustomBusinessDay.base
next
pandas.tseries.offsets.CustomBusinessDay.kwds