class Testo(
	val value: Int
) {
     companion object parse {
          operator fun invoke(value: Int): Testo {
              return Testo(value + 1);
          }
     }
}

fun main(args: Array<String>) {
    println(Testo(1).value)
}

in

infix fun <T> Collection<T>.by(equalityComparator: (T, T) -> Boolean) : Collection<T> {

something !in someCollection by YourType::theMethodToCompareUsing

by

list.any {}

someList.removeAll { it !in anotherList by MyType::isSpecialEquals } 
someList.removeAll { candidate -> anotherList.any { it.isSpecialEquals(candidate) } }

which requires the creation of a weird object as the return value from

by

by

standard.kt

Collections.kt