Python 3; include doc strings.

1. Write a function to compute the mean ? of a list of integers L of length n Tn Motivation: we are assuming that cach clement of L occurs w ith equal probability so we are weighting cach one by TL 2. Write a function to compute the variance V of a list of integers L of length n: V= TI, Tn This measures the spread or dispersion of the data. 3. Write a function to compute the standard deviation D of a list of intcgers L; if the variance of L is V then the standard deviation is