new_contents: """
  GEOMETRIC MEAN :  https://en.wikipedia.org/wiki/Geometric_mean
  """
  
  
  def is_geometric_series(series: list) -> bool:
      """
      checking whether the input series is geometric series or not
  
      >>> is_geometric_series([2, 4, 8])
      True
      >>> is_geometric_series([3, 6, 12, 24])
      True
      >>> is_geometric_series([1, 2, 3])
      False
      >>> is_geometric_series([0, 0, 3])
      False
  
      """
      if len(series) == 1:
          return True
      try:
          common_ratio = series[1] / series[0]
          for index in range(len(series) - 1):
              if series[index + 1] / series[index] != common_ratio:
                  return False
      except ZeroDivisionError:
          return False
      return True
  
  
  def geometric_mean(series: list) -> float:
      """
      return the geometric mean of series
  
      >>> geometric_mean([2, 4, 8])
      3.9999999999999996
      >>> geometric_mean([3, 6, 12, 24])
      8.48528137423857
      >>> geometric_mean([4, 8, 16])
      7.999999999999999
      >>> geometric_mean(4)
      Traceback (most recent call last):
          ...
      ValueError: Input series is not valid, valid series - [2, 4, 8]
      >>> geometric_mean([1, 2, 3])
      Traceback (most recent call last):
          ...
      ValueError: Input list is not a geometric series
      >>> geometric_mean([0, 2, 3])
      Traceback (most recent call last):
          ...
      ValueError: Input list is not a geometric series
      >>> geometric_mean([])
      Traceback (most recent call last):
          ...
      ValueError: Input list must be a non empty list
  
      """
      if not isinstance(series, list):
          raise ValueError("Input series is not valid, valid series - [2, 4, 8]")
      if len(series) == 0:
          raise ValueError("Input list must be a non empty list")
      if not is_geometric_series(series):
          raise ValueError("Input list is not a geometric series")
      answer = 1
      for value in series:
          answer *= value
      return pow(answer, 1 / len(series))
  
  
  if __name__ == "__main__":
      import doctest
  
      doctest.testmod()
  
subject: Add geometric_mean.py (#4244)