What is the default implementation of Set in Kotlin?

What is the default implementation of a Map in Kotlin?

What will be the output of this referential equality comparison?

val someList = listOf(1, 2, 3, 4)
val filteredList = someList.filter { it % 2 == 0 }
println(someList === filteredList)

How can we check if a range contains element x?

Which sentence is correct in terms of Sequences multi-step processing? Example:

sequenceOf(1, 2, 3, 4)
  .map { it * 10 }
  .filter { it % 3 == 0 }

Which sentence is correct in terms of Iterable multi-step processing? Example:

listOf(1, 2, 3, 4)
  .map { it * 10 }
  .filter { it % 3 == 0 }