message: Added variable "self" to perfect_tree_pivot()
diff: @@ -18,7 +18,7 @@ class Solution:
  return self.sortedArrayToBSTRecu(num, 0, len(num))
  @staticmethod
  - def perfect_tree_pivot(n):
  + def perfect_tree_pivot(self, n):
  """
  Find the point to partition n keys for a perfect binary search tree
  """
  