Add more detailed error messages for the RB assignment

notes-and-examples/2026.07.01/red_black_tree.py

@@ -1,3 +1,5 @@
+import traceback
+
 class Node:
     def __init__(self, value, left=None, right=None, parent=None, is_red=False):
         self.value = value
@@ -451,8 +453,10 @@ def run_tests():
             print("    Your rebalance likely created a cycle or otherwise broke the")
             print("    tree structure (a child pointing back up at an ancestor).\n")
             continue
-        except Exception as e:
-            print(f"  RESULT: ERROR - {type(e).__name__}: {e}\n")
+        except Exception:
+            print(f"  RESULT: ERROR - see stack trace below\n")
+            print(traceback.format_exc())
+            print("")
             continue
 
         # Guard the author (you) against a typo when adding a new case: the