input: Write a function to calculate the average of five numbers entered by a user and print the result. The function should take no input parameters and return the average value.
  assert calculate_average() == 3.0
  assert calculate_average() == 4.5
  assert calculate_average() == 7.0
  assert calculate_average() == 2.8
  assert calculate_average() == 5.6
output: def calculate_average():
      numbers = []
      for i in range(5):
          numbers.append(float(input()))
      return sum(numbers) / len(numbers)