Implement a minimal `Option` that has `map` and `flatMap`.

import scala.{Option => _}

// TODO: Implement here



sealed trait Option[+T] { 
    def map[B](f: T => B): Option[B] = {
        this match {
            case Some(v) => Some(f(v))
            case None => None
        }
    }
    
    def flatMap[B](f: T => Option[B]): Option[B] = {
        this match {
            case Some(v) => f.apply(v)
            case None => None
        }
    }
    
    def fold[B](b:B)(f:T => B): B = {
        this match {
            case Some(v) => f(v)
            case None => b
        }
    }
}

case class Some[+T](t: T) extends Option[T]
case object None extends Option[Nothing]



val s: Option[Int] = Some(10)

// use fold on s
s.fold("")(b => s"some string $b")
























val someAnimal: Option[Animal] = ???
val someMonkey: Option[Monkey] = ???
val none = None

def f(o: Option[Animal]) = ???

f(someMonkey)