text: def flatten_list(arr):
      result = []
      for item in arr:
          if isinstance(item, list):
              result.extend(flatten_list(item))
          else:
              result.append(item)
      return result
  
  def flatten_list(mapping):
      for key in mapping:
          if isinstance(mapping[key], dict):
              value = mapping[key]
  
  
  if __name__ == '__main__':
      print(flatten_list([1, 2, [3, 4, 5, [6, 7, [11, 12, [13, 14]]], 8], 9]))