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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 average(arr):
 """average of the values, must have more than 0 entries. :param arr: list of numbers :type arr: number[] a number array :return: average :rtype: float """

  if len(arr) == 0:
    sys.stderr.write("ERROR: no content in array to take average\n")
    sys.exit()
  if len(arr) == 1:  return arr[0]
  return float(sum(arr))/float(len(arr))