Node Modules: How do modules work in node? If a variable is declared at the top level and exported, what is the scope? Databases: What is a relational DB? What is a Document-based DB? What are the differences in SQL vs NoSQL? * Strengths and weaknesses of a relational DB? * Strengths and weaknesses of a Document DB? What are streams in node and how do they work? What uses cases are good for streams?