How many users were there?

The question "How many users were there?" is too general and depends on the project context. Usually, users refer to active users over a certain period (for example, DAU — daily active users).

If it is about a system written in Go, then the number of users can be measured by monitoring metrics, logs, or analytics. For example, counters in a database or external analytics services can be used.

To give an accurate answer, it is necessary to specify which project or system is being referred to.