func_code: def parition(a, p, r):
      q = j = p
      while j < r:
          if a[j] <= a[r]:
              a[q], a[j] = a[j], a[q]
              q += 1
          j += 1
      a[q], a[r] = a[r], a[q]
  
  
  def quicksort(a, p, r):
      if r <= p:
          return
      else:
          q = parition(a, p, r)
          quicksort(a, p, q - 1)
          quicksort(a, q + 1, r)