input: Write a function to calculate the average of five numbers entered by a user. Each number should be entered one by one and then the average should be calculated and printed.
  assert calculate_average([1, 2, 3, 4, 5])==3.0
  assert calculate_average([10, 20, 30, 40, 50])==30.0
  assert calculate_average([0, 0, 0, 0, 0])==0.0
  assert calculate_average([-1, 2, -3, 4, -5])==-0.6
  assert calculate_average([1, 1, 1, 1, 1])==1.0
output: def calculate_average(numbers):
      return sum(numbers) / len(numbers)