// The below code results in a compilation error
data class ViewModel(
    var lineSpeed: Int? = null
)

val viewModel = ViewModel()

if(viewModel.lineSpeed != null && viewModel?.lineSpeed > 0 ) {}

//Error : Smart cast to 'Int' is impossible, because 'viewModel.lineSpeed' is a mutable property that could have been changed by this time

!!

viewModel.lineSpeed?.takeIf { it > 0 }?.let {

}

fun Int?.isGreaterThan(a: Int) = this != null && this > a

if (viewModel.lineSpeed.isGreaterThan(3)) {

}