db={"A":[{"_id":ObjectId("5f67883478d0182ebcc2fc31"),"data":"god"},{"_id":ObjectId("5f67883478d0182ebcc2fc30"),"data":"demon"}],"B":[{"_id":ObjectId("5f6797b578d0182ebcc2fc35"),"title":"Book D","description":"blah blah"},{"_id":ObjectId("5f67887178d0182ebcc2fc34"),"title":"Book C","description":"this book is about a dog."},{"_id":ObjectId("5f67887178d0182ebcc2fc33"),"title":"Book B","description":"this book is about a god from Greek."},{"_id":ObjectId("5f67887178d0182ebcc2fc32"),"title":"Book A","description":"this book is about a demon."}]}

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