[langchain]: ImportError: cannot import name 'ModelRequestHandler' from 'langchain.agents.middleware'

[mcavdar]

Type of issue

issue / bug

Language

Python

Description

from langchain.agents.middleware import (
    AgentMiddleware,
    ModelRequest,
    ModelRequestHandler
)

Running the imports from this page results in the following error:
ImportError: cannot import name 'ModelRequestHandler' from 'langchain.agents.middleware'

I’ll update the examples soon based on the new documentation at: https://docs.langchain.com/oss/python/langchain/middleware#custom-middleware.