fix some style errors

Author: rafaelleru

data_structures/Binary Tree/binary_seach_tree.py

@@ -1,6 +1,8 @@
 '''
 A binary search Tree
 '''
+
+
 class Node:
 
  def __init__(self, label):
@@ -34,7 +36,7 @@ def __init__(self):
 
  def insert(self, label):
 
- #Create a new Node
+ # Create a new Node
 
  node = Node(label)
 
@@ -45,7 +47,7 @@ def insert(self, label):
  curr_node = self.root
 
  while True:
- if curr_node != None:
+ if curr_node is not None:
 
  dad_node = curr_node
 
@@ -61,12 +63,12 @@ def insert(self, label):
  break
 
  def empty(self):
- if self.root == None:
+ if self.root is None:
  return True
  return False
 
  def preShow(self, curr_node):
- if curr_node != None:
+ if curr_node is None:
  print(curr_node.getLabel(), end=" ")
 
  self.preShow(curr_node.getLeft())