From 887f9e5b01c36ae3fb24355046c78ab3aee390dd Mon Sep 17 00:00:00 2001
From: Akshay Sharma <akshay.sharma09695@gmail.com>
Date: Fri, 14 Oct 2016 00:01:44 +0530
Subject: [PATCH 1/2] added isinstance check

---
 traverals/binary_tree_traversals.py | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/traverals/binary_tree_traversals.py b/traverals/binary_tree_traversals.py
index c1e8783b2..6b0dd5ee9 100644
--- a/traverals/binary_tree_traversals.py
+++ b/traverals/binary_tree_traversals.py
@@ -40,7 +40,8 @@ def build_tree():
 
 
 def pre_order(node):
-    if not node:
+    if not isinstance(node, TreeNode) or not node:
+        print("Invalid input")
         return
     print(node.data, end=" ")
     pre_order(node.left)
@@ -48,7 +49,8 @@ def pre_order(node):
 
 
 def in_order(node):
-    if not node:
+     if not isinstance(node, TreeNode) or not node:
+        print("Invalid input")
         return
     in_order(node.left)
     print(node.data, end=" ")
@@ -56,7 +58,8 @@ def in_order(node):
 
 
 def post_order(node):
-    if not node:
+     if not isinstance(node, TreeNode) or not node:
+        print("Invalid input")
         return
     post_order(node.left)
     post_order(node.right)
@@ -64,7 +67,8 @@ def post_order(node):
 
 
 def level_order(node):
-    if not node:
+     if not isinstance(node, TreeNode) or not node:
+        print("Invalid input")
         return
     q = queue.Queue()
     q.put(node)

From d62e8e28681819b17077782202881a13ee64dfe4 Mon Sep 17 00:00:00 2001
From: Akshay Sharma <akshay.sharma09695@gmail.com>
Date: Fri, 14 Oct 2016 01:27:52 +0530
Subject: [PATCH 2/2] travis cli build fail

---
 traverals/binary_tree_traversals.py | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/traverals/binary_tree_traversals.py b/traverals/binary_tree_traversals.py
index 6b0dd5ee9..591142b27 100644
--- a/traverals/binary_tree_traversals.py
+++ b/traverals/binary_tree_traversals.py
@@ -6,7 +6,6 @@ import queue
 
 
 class TreeNode:
-
     def __init__(self, data):
         self.data = data
         self.right = None
@@ -49,8 +48,7 @@ def pre_order(node):
 
 
 def in_order(node):
-     if not isinstance(node, TreeNode) or not node:
-        print("Invalid input")
+    if not isinstance(node, TreeNode) or not node:
         return
     in_order(node.left)
     print(node.data, end=" ")
@@ -58,8 +56,7 @@ def in_order(node):
 
 
 def post_order(node):
-     if not isinstance(node, TreeNode) or not node:
-        print("Invalid input")
+    if not isinstance(node, TreeNode) or not node:
         return
     post_order(node.left)
     post_order(node.right)
@@ -67,8 +64,7 @@ def post_order(node):
 
 
 def level_order(node):
-     if not isinstance(node, TreeNode) or not node:
-        print("Invalid input")
+    if not isinstance(node, TreeNode) or not node:
         return
     q = queue.Queue()
     q.put(node)
@@ -83,6 +79,7 @@ def level_order(node):
 
 if __name__ == '__main__':
     import sys
+
     print("\n********* Binary Tree Traversals ************\n")
     # For python 2.x and 3.x compatibility: 3.x has not raw_input builtin
     # otherwise 2.x's input builtin function is too "smart"