Practically, what ways to "type your side effects" are useful and not only mandatory formalities to appease the compiler? For example, writing something or som

Practically, what ways to "type your side effects" are useful and not only mandatory formalities to appease the compiler? For example, writing something or something else or nothing at all to the standard output doesn't appear likely to influence the execution of the rest of the program, even if formally the program is in a different state.