def stdev ( self ) : return round ( np . std ( self . array ) , self . precision ) if len ( self . array ) else None
python numpy calculate stdev
- > #float : func : numpy . std of the timing intervals
def stdev(self):
        """ -> #float :func:numpy.std of the timing intervals """
        return round(np.std(self.array), self.precision)\
            if len(self.array) else None