langchain

ec9642d6 - docs: Updated MongoDB Chat history example notebook to use LCEL format. (#15750)

docs: Updated MongoDB Chat history example notebook to use LCEL format. (#15750) - **Description:** Updated the MongoDB example integration notebook to latest standards - **Issue:** [15664](https://github.com/langchain-ai/langchain/issues/15664) - **Dependencies:** None - **Twitter handle:** @davedecaprio --------- Co-authored-by: Harrison Chase <hw.chase.17@gmail.com>