adding static type checking to basic_binary_tree.py

data_structures/binary_tree/basic_binary_tree.py

@@ -4,13 +4,13 @@ class Node:
     and left, right pointers.
     """
 
-    def __init__(self, data):
+    def __init__(self, data: int) -> None:
         self.data = data
-        self.left = None
-        self.right = None
+        self.left: Optional[Node] = None
+        self.right: Optional[Node] = None
 
 
-def display(tree):  # In Order traversal of the tree
+def display(tree: Node) -> None:  # In Order traversal of the tree
 
     if tree is None:
         return
@@ -26,9 +26,11 @@ def display(tree):  # In Order traversal of the tree
     return
 
 
-def depth_of_tree(
-    tree,
-):  # This is the recursive function to find the depth of binary tree.
+def depth_of_tree(tree: Node,) -> int:
+    """
+    Recursive function that finds the depth of a binary tree.
+    """
+
     if tree is None:
         return 0
     else:
@@ -40,9 +42,11 @@ def depth_of_tree(
             return 1 + depth_r_tree
 
 
-def is_full_binary_tree(
-    tree,
-):  # This function returns that is it full binary tree or not?
+def is_full_binary_tree(tree: Node,) -> bool:
+    """
+    Returns True if this is a full binary tree
+    """
+
     if tree is None:
         return True
     if (tree.left is None) and (tree.right is None):
@@ -53,7 +57,7 @@ def is_full_binary_tree(
         return False
 
 
-def main():  # Main function for testing.
+def main() -> None:  # Main function for testing.
     tree = Node(1)
     tree.left = Node(2)
     tree.right = Node(3)