What is users variable in this SqlBrite example? what is its initial value?

I copied given below example from http://ift.tt/1FdSAeu

 final AtomicInteger count = new AtomicInteger();
 users.subscribe(new Action1<Query>() 
 {
        @Override public void call(Query query) 
        {
          count.getAndIncrement();
        }
});

System.out.println("Queries: " + count.get()); // Prints 1

db.insert("user", createUser("jw", "Jake Wharton"));
db.insert("user", createUser("mattp", "Matt Precious"));
db.insert("user", createUser("strong", "Alec Strong"));

System.out.println("Queries: " + count.get()); // Prints 4

My question is simple that what is users in given example, what should i initialize to ?