Replace langchain legacy imports with langchain_classic

Proprietary

Migrate legacy chain, retriever, and indexing imports from langchain to langchain_classic. These were moved in LangChain v1.0. Only from langchain... import ... statements are rewritten. import langchain.chains and the references made through it are left unchanged.

org.openrewrite.python.migrate.langchain.ReplaceLangchainClassicImports
mod run . --recipe=org.openrewrite.python.migrate.langchain.ReplaceLangchainClassicImports

Install it once, then run it on every repository under the current directory. New to the Moderne CLI? Set it up.