Basically, I'm coding a poker app and I have a class called `Deck` which is really just a `List<>` contain objects of the class `Card`. It's literally just a list of cards.

I'm now trying to concatenate two of these `Decks` together: `playerCards` and `tableCards`. However, when I write this code, I get an error message:

```
playerCards.Concat(tableCards);

```

It tells me that "'Deck' does not contain a definition for 'Concat' and no extension method 'Concat' accepting a first argument of type 'Deck' could be found."

How can I concatenate these two list objects together?

Hopefully this explains Deck a bit better...

```
public class Deck
{

    public Deck()
    {
        deck = new List<Card>();
    }

    public List<Card> deck { get; }

```