I hardly know code.. This (I hafta admit) is only a piece of code from a Good textbook on making Swift& Spritekit games!! -Any suggestions or observations on why I got the error please.

To clarify, I do have fairly major cognitive issues..:

import Foundation
import SpriteKit
//MARK: SPRITEKIT EXTENSIONS
extension SKSpriteNode{
func loadTextures(atlas: String, prefix: String,
                      startsAt: Int, stopsAt: Int) -> [SKTexture] {
        var textureArray = [SKTexture]()
        let textureAtlas = SKTextureAtlas(named: atlas)
        for i in startsAt...stopsAt {
            let textureName = "\(prefix)\(i)"
            let temp = textureAtlas.textureNamed(textureName)
            textureArray.append(temp)
        )
        return textureArray
        
        }
    }
}