langchain/memory/chat_message_histories/cosmos_db.py/CosmosDBChatMessageHistory/prepare_cosmos
class CosmosDBChatMessageHistory:    def prepare_cosmos(self) -> None:
        """Prepare the CosmosDB client.

        Use this function or the context manager to make sure your database is ready.
        """
        try:
            from azure.cosmos import (  # pylint: disable=import-outside-toplevel # noqa: E501
                PartitionKey,
            )
        except ImportError as exc:
            raise ImportError(
                "You must install the azure-cosmos package to use the CosmosDBChatMessageHistory."  # noqa: E501
            ) from exc
        database = self._client.create_database_if_not_exists(self.cosmos_database)
        self._container = database.create_container_if_not_exists(
            self.cosmos_container,
            partition_key=PartitionKey("/user_id"),
            default_ttl=self.ttl,
        )
        self.load_messages()