input: from typing import List
  
  
  def mean_median(arr: List[float]) -> tuple:
      """Given a list of numbers, calculate the mean and median.
      >>> mean, median = mean_median([10, 15, 20, 25, 30, 35])
      >>> print(f"Mean = {mean}, Median = {median}")
      Mean = 22.5, Median = 22.5
      """
      arr_sum = 0
      for i in range(len(arr)):
          arr_sum += arr[i]
  
      mean = arr_sum / len(arr)
  
      arr = sorted(arr)
      if len(arr) % 2 != 0:
          median = arr[len(arr) // 2]
      else:
          median = (arr[len(arr) // 2] + arr[len(arr) // 2 - 1]) / 2
  
      return mean, median
output:     arr_sum = 0
      for i in range(len(arr)):
          arr_sum += arr[i]
  
      mean = arr_sum / len(arr)
  
      arr = sorted(arr)
      if len(arr) % 2 != 0:
          median = arr[len(arr) // 2]
      else:
          median = (arr[len(arr) // 2] + arr[len(arr) // 2 - 1]) / 2
  
      return mean, median