I had this code written by a user here yesterday and I'm having trouble understanding it. I understand all by line 9 of the deal function, it creates a random card out of 52 numbers but on the next line I don't understand what this does. Could somebody please explain what this code does so I could modify it and expand on it?

```
//Creates the deck
var Ace = 1;
var Face = 10;
var deck = [Ace, 2, 3, 4, 5, 6, 7, 8, 9, 10, Face, Face, Face];
/*Creates a deal function that can deal cards to each player. 
Use object_name.property_name = deal() to call this function.*/
var deal = function () {
    var randomcard = Math.ceil(Math.random() * 52) + 1;
    return deck[Math.floor(randomcard % 13)];
};

```