Anybody can tell me how is it works? Please!

See in the Kotlin Coding conventions (V2.0.21) the sections functions:

fun foo(): Int {     // bad
    return 1
}

fun foo() = 1        // good

That's really awesome solution! You amazed me.

That's very easy task for all Java's users. I think, that it task is easely than other task's.

Wow! That's cool!