diff --git a/tries/trie_find_height.py b/tries/trie_find_height.py
index c37410f..618ff8a 100644
--- a/tries/trie_find_height.py
+++ b/tries/trie_find_height.py
@@ -15,25 +15,27 @@ def max_depth_recursive(root):
     if root is None:
             return 0
 
-    if root.children == []:
+    if root.children: is None:
             return 1
 
-    height = [max_depth_recursive(c) for c in root.children]
-    return max(height) + 1
+    height = [max_depth_recursive(children) for children in root.children]
+    
+   return max(height) + 1
 
 
 def max_depth_iterative(root):
 
-        stack = []
+        stack, depth = [], 0
+  
         if root is not None:
             stack.append((1, root))
 
-        depth = 0
-
-        while stack != []:
+        while stack:
             
             this_depth, node = stack.pop()
+          
             if node is not None:
+              
                 depth = max(depth, this_depth)
                 for c in node.children:
                     stack.append((this_depth + 1, c))