From 5d6b83d9cf96409d61573b3fd864bccab8cd43a6 Mon Sep 17 00:00:00 2001
From: Predrag Gruevski <2348618+obi1kenobi@users.noreply.github.com>
Date: Tue, 3 Oct 2023 15:27:51 -0400
Subject: [PATCH] Make a copy of external data instead of mutating another
 object's attributes. (#11349)

Fix for a bug surfaced as part of #11339. `mypy` caught this since the
types didn't match up.
---
 .../comprehend_moderation/base_moderation.py                 | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/libs/experimental/langchain_experimental/comprehend_moderation/base_moderation.py b/libs/experimental/langchain_experimental/comprehend_moderation/base_moderation.py
index 3724ac081d..9af9144773 100644
--- a/libs/experimental/langchain_experimental/comprehend_moderation/base_moderation.py
+++ b/libs/experimental/langchain_experimental/comprehend_moderation/base_moderation.py
@@ -70,7 +70,10 @@ class BaseModeration:
         elif isinstance(prompt, str):
             return text
         elif isinstance(prompt, ChatPromptValue):
-            messages = prompt.messages
+            # Copy the messages because we may need to mutate them.
+            # We don't want to mutate data we don't own.
+            messages = list(prompt.messages)
+
             message = messages[self.chat_message_index]
 
             if isinstance(message, HumanMessage):