Option

sealed class Option<out T>

Represents an optional value with map, flatMap, fold and getOrElse to transform it.

filter	`fun filter(predicate: (T) -> Boolean): Option<T>`
flatMap	`fun <R> flatMap(f: (T) -> Option<R>): Option<R>`
fold	`fun <R> fold(default: () -> R, f: (T) -> R): R`
isDefined	`fun isDefined(): Boolean`
map	`fun <R> map(f: (T) -> R): Option<R>`

fun <T> someIf(predicate: Boolean, provider: () -> T): Option<T>

fun <T> Option<T>.getOrElse(default: () -> T): T

None	`object None : Option<Nothing>`
Some	`data class Some<T> : Option<T>`