input: 
  def mean_median(arr): 
      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
  
  mean, median = mean_median([10, 15, 20, 25, 30, 35]) 
  assert mean == 22.5 
  assert median == 22.5
  
output:     mean, median = mean_median([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) 
      assert mean == 5.5 
      assert median == 5.5