fix: do not allow duplicit keys

Signed-off-by: Matej Focko <mfocko@redhat.com>

node.py

@@ -146,7 +146,12 @@ class Node(Generic[T]):
 
         while new_node and (missing or new_node.value != value):
             node = new_node
-            new_node = node.left if value < node.value else node.right
+            if value < node.value:
+                new_node = node.left
+            elif node.value < value:
+                new_node = node.right
+            else:
+                return None
 
         return node
 

ranked_tree.py

@@ -82,6 +82,9 @@ class RankedTree(Generic[T]):
             return
 
         parent = Node.find_parent_node(value, self.root)
+        if not parent:
+            return
+
         inserted_node.parent = parent
 
         if value < parent.value: