langchain/libs/community/langchain_community/indexes/__init__.py

"""**Index** is used to avoid writing duplicated content
into the vectostore and to avoid over-writing content if it's unchanged.

Indexes also :

* Create knowledge graphs from data.

* Support indexing workflows from LangChain data loaders to vectorstores.

Importantly, Index keeps on working even if the content being written is derived
via a set of transformations from some source content (e.g., indexing children
documents that were derived from parent documents by chunking.)
"""