input: Write a python function to calculate the average of a list of numbers.
  assert calculate_average([4, 6, 8, 10, 11, 12, 22, 34, 36, 37]) == 19.0
  assert calculate_average([1, 2, 3, 4, 5]) == 3.0
  assert calculate_average([10, 20, 30, 40, 50]) == 30.0
output: def calculate_average(numbers):
      return sum(numbers) / len(numbers)