So far, when writing these subscribe functions, we haven't returned anything. It is possible return an unsubscribe function from a subscribe function. In this lesson we will see how to allow observers to subscribe and unsubscribe from an Observable.
To keep code elegant and readable, this lesson presents a refactoring technique consisting of two rules: (1) Don't have empty lines in a function, (2) keep the function short, with at most 6 or 8 statements. See how this can help keep each function focused on one responsibility.