Update basic_binary_tree.py (TheAlgorithms#725)

I have added the comments for better understanding.

Author: AkashAli506

binary_tree/basic_binary_tree.py

@@ -1,11 +1,11 @@
-class Node:
+class Node: # This is the Class Node with constructor that contains data variable to type data and left,right pointers.
     def __init__(self, data):
         self.data = data
         self.left = None
         self.right = None
 
 
-def depth_of_tree(tree):
+def depth_of_tree(tree): #This is the recursive function to find the depth of binary tree.
     if tree is None:
         return 0
     else:
@@ -17,7 +17,7 @@ def depth_of_tree(tree):
             return 1 + depth_r_tree
 
 
-def is_full_binary_tree(tree):
+def is_full_binary_tree(tree): # This functions returns that is it full binary tree or not?
     if tree is None:
         return True
     if (tree.left is None) and (tree.right is None):
@@ -28,7 +28,7 @@ def is_full_binary_tree(tree):
         return False
 
 
-def main():
+def main(): # Main func for testing.
     tree = Node(1)
     tree.left = Node(2)
     tree.right = Node(3)