Kotlin Online Test

The following Kotlin code is used in a toy drone to adjust its movement:

fun adjust(vertical: Int?, horizontal: Int?) : Unit {
    if (vertical == null) {
        println("Didn't get vertical information")
    } else {
        // Controls the drone with amplified vertical movements
        move(vertical * 2, horizontal!!)
    }
    log_movement(vertical ?: -1, horizontal ?: -1)
}

Select the correct answers about the adjust function.

Consider the following code used to check whether two materials are compatible to use in a construction project:

enum class Category {
    HEAVY, LIGHT, FILLER
}

data class Material (val category: Category)

// Extension infix function.
infix fun Material.compatibleWith(other: Material) : Boolean {
    return this.category == Category.LIGHT || other.category == Category.FILLER;
}

fun main() {
    val mat1 = Material(Category.HEAVY)
    val mat2 = Material(Category.LIGHT)
    // Use mat1 and mat2 here.
}

What is correct about the compatibleWith function?