text: ),    Document(        page_content="Morbi tortor enim, commodo id efficitur vitae, fringilla nec mi. Nullam molestie faucibus aliquet. Praesent a est facilisis, condimentum justo sit amet, viverra erat. Fusce volutpat nisi vel purus blandit, et facilisis felis accumsan. Phasellus luctus ligula ultrices tellus tempor hendrerit. Donec at ultricies leo.",         metadata={"id": 87732, "date": "2022-11-13T18:49:04.000000Z"}    )]Using multiple columns as contentâ€‹You can choose to use multiple columns as content:from langchain.document_loaders import RocksetLoaderfrom rockset import RocksetClient, Regions, modelsloader = RocksetLoader(    RocksetClient(Regions.usw2a1, "<api key>"),    models.QueryRequestSql(query="SELECT * FROM langchain_demo LIMIT 1 WHERE id=38"),    ["sentence1", "sentence2"],  # TWO content columns)Assuming the "sentence1" field is "This is the first sentence." and the "sentence2" field is "This is the second sentence.", the page_content of the resulting Document would be:This is the first sentence.This is the second sentence.You can define you own function to join content columns by setting the content_columns_joiner argument in the RocksetLoader constructor. content_columns_joiner is a method that takes in a List[Tuple[str, Any]]] as an argument, representing a list of tuples of (column name, column value). By default, this is a method that joins each column value with a new line.For example, if you wanted to join sentence1 and sentence2 with a