input: Write a python function to calculate the mean and standard deviation of a list of numbers.
  assert calculate_statistics([3,3,3,3,3]) == (3, 0.0)
  assert calculate_statistics([1,2,3,4,5]) == (3, 1.5811388300841898)
  assert calculate_statistics([10,20,30,40,50]) == (30, 15.811388300841896)
output: def calculate_statistics(numbers):
      import math
      
      mean = sum(numbers) / len(numbers)
      variance = sum((x - mean) ** 2 for x in numbers) / len(numbers)
      std_deviation = math.sqrt(variance)
      
      return mean, std_deviation