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
  
  """
  Compute the mean and median of a given array.
  
  >>> mean, median = mean_median([10, 15, 20, 25, 30, 35])
  >>> mean
  22.5
  >>> median
  22.5
  """
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