from math import *

def setup_data_list(data_length,starting_value):
  #global data_length
  #data_length=5
  pointer=0
  data_list = [starting_value for x in range(data_length)]
  return [data_list,pointer]
  
def update_list(data_structure,new_data):
  data_list=data_structure[0]
  pointer=data_structure[1]
  pointer=pointer+1
  if pointer==len(data_list):
    pointer=0
  data_list[pointer]=new_data
  return [data_list,pointer]