// Part 2 about finding a single tour for a board//================================================// copy any function you need from file knight1.scalaobject CW7b {type Pos = (Int, Int) // a position on a chessboard type Path = List[Pos] // a path...a list of positions//(2a) Implement a first-function that finds the first // element, say x, in the list xs where f is not None. // In that case Return f(x), otherwise None. If possible,// calculate f(x) only once.//def first(xs: List[Pos], f: Pos => Option[Path]) : Option[Path] = ...//(2b) Implement a function that uses the first-function for// trying out onward moves, and searches recursively for a// knight tour on a dim * dim-board.//def first_tour(dim: Int, path: Path) : Option[Path] = ...}