Can you give an example of code that does not change when executed and does not cause side effects?

An example of code without state changes and side effects is a pure function. It always returns the same result for the same inputs and does not modify external state.

Example in Kotlin for Android:

fun sum(a: Int, b: Int): Int {
    return a + b
}

This function does not modify any variables outside itself and does not cause side effects — it simply returns the sum of its arguments.

Another example is retrieving a string from resources without modifications:

fun getWelcomeMessage(): String {
    return "Welcome!"
}

Such functions are easy to test and predictable.