119 def _sum(data, start=0):  argument
294 def _counts(data):  argument
310 def mean(data):  argument
337 def median(data):  argument
361 def median_low(data):  argument
383 def median_high(data):  argument
402 def median_grouped(data, interval=1):  argument
451 def mode(data):  argument
493 def _ss(data, c=None):  argument
513 def variance(data, xbar=None):  argument
560 def pvariance(data, mu=None):  argument
609 def stdev(data, xbar=None):  argument
625 def pstdev(data, mu=None):  argument