Defining and Calculating User Sessions

Imagine you're tasked with analyzing event data from users on a social media platform similar to Facebook. A product manager is eager to determine the average daily number of "sessions." However, the company hasn't formally defined what constitutes a "session." The product manager suggests a scenario where a user accesses Facebook on their phone in the morning and revisits during lunch, treating these as two separate "sessions." This implies a gap where the user exits Facebook to engage in other activities before returning. With a dataset of raw user events, how would you establish a definition for a "session" that aligns with the company's needs? Based on your definition, craft a query to calculate the average number of sessions per day.