langchain/vectorstores/mongodb_atlas.py/MongoDBAtlasVectorSearch/from_connection_string
class MongoDBAtlasVectorSearch:    def from_connection_string(
        cls,
        connection_string: str,
        namespace: str,
        embedding: Embeddings,
        **kwargs: Any,
    ) -> MongoDBAtlasVectorSearch:
        try:
            from pymongo import MongoClient
        except ImportError:
            raise ImportError(
                "Could not import pymongo, please install it with "
                "`pip install pymongo`."
            )
        client: MongoClient = MongoClient(connection_string)
        return cls(client, namespace, embedding, **kwargs)