If anyone is able, would you please explain to me these two questions from the quiz? I’m stumped.

Why does `toSeq` compile, but not `toIndexedSeq`?

    Set(1,2,3).toIndexedSeq sortBy (-_)
    Set(1,2,3).toSeq sortBy (-_)

Why does `h` compile, but `f` does not?

    def add(x: Int, y: Int) = x + y
    val f = add(1,_)
    val h = add(_,_)