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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def variance(arr):
 """variance of the values, must have 2 or more entries. :param arr: list of numbers :type arr: number[] a number array :return: variance :rtype: float """

  avg = average(arr)
  return sum([(float(x)-avg)**2 for x in arr])/float(len(arr)-1)