input: Write a python function to calculate the standard deviation of a list of numbers.
  assert calculate_std_dev([3, 7, 12, 22, 35]) == 11.10630409715702
  assert calculate_std_dev([10, 20, 30, 40, 50]) == 14.142135623730951
  assert calculate_std_dev([1, 2, 3, 4, 5]) == 1.4142135623730951
output: def calculate_std_dev(numbers):
      mean = sum(numbers) / len(numbers)
      variance = sum((x - mean) ** 2 for x in numbers) / len(numbers)
      return variance ** 0.5