# stats.py
#   Functions for simple statistic program

def get_scores():
    '''Gets scores interactively from the user

    post: returns a list of numbers obtained from user

    '''

def min_value(nums):
    ''' find the minimum

    pre: nums is a list of numbers
    post: returns smallest number in nums

    '''

def max_value(nums):
    ''' find the maximum

    pre: nums is a list of numbers
    post: returns largest number in nums

    '''

def average(nums):
    ''' calculate the mean

    pre: nums is a list of numbers
    post: returns the mean (a float) of the values in nums

    '''

def std_deviation(nums):
    '''calculate the standard deviation

    pre: nums is a list of numbers
    post: returns the standard deviation (a float) of the values in nums

    '''
    
    xbar = average(nums)
    sum = 0
    for num in nums:
        sum += (xbar - num)**2
    return math.sqrt(float(sum) / (len(nums) - 1))