How to use SKSpriteNode when declaring functions in spritekit (Swift)

This is my first game using SpriteKit so bear with this question. I am trying to create a function for my blackjack game where I distribute two cards, each for the player. Here is the function:

func distribution(card: SKSpriteNode, x_position: CGFloat, y_position: CGFloat) {
            let card = SKSpriteNode(imageNamed: cards[0])
            card.setScale(0.1)
            card.position = CGPoint(x: x_position, y: y_position)
            card.zPosition = 2
            self.addChild(card)
            cards.remove(at: 0)
        }
        distribution(card: player_card_1 , x_position: self.size.width/2 + self.size.width/5 - self.size.width/12, y_position: self.size.height/3)
        distribution(card: player_card_2, x_position: self.size.width/4 + self.size.width/12, y_position: self.size.height/3)

the variable cards is already a predefined array with the cards However, by doing this, it is giving me errors: Cannot find 'player_card_1' and 'player_card_2' in scope.

And I didn't predefine player_card_1 and player_card_2, just defined it when I called the distribution function

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