105 def _sum(data, start=0):  argument
251 def _counts(data):  argument
291 def mean(data):  argument
317 def harmonic_mean(data):  argument
364 def median(data):  argument
388 def median_low(data):  argument
410 def median_high(data):  argument
429 def median_grouped(data, interval=1):  argument
484 def mode(data):  argument
526 def _ss(data, c=None):  argument
546 def variance(data, xbar=None):  argument
593 def pvariance(data, mu=None):  argument
641 def stdev(data, xbar=None):  argument
657 def pstdev(data, mu=None):  argument