input: Write a function to calculate the average of five numbers entered by a user. The function should prompt the user to enter each number one by one, calculate the average, and print the result.
  assert calculate_average([3, 4, 5, 1, 2]) == 3.0
  assert calculate_average([8, 9, 10, 11, 12]) == 10.0
  assert calculate_average([1, 1, 1, 1, 1]) == 1.0
output: def calculate_average(numbers):
      total = sum(numbers)
      average = total / len(numbers)
      return average