This is a simple shopping cart API in node built using event sourcing

## Concepts

A product consists of:

• An ID
• A name
• A description
• A price

{
    "id": 1,
    "name": "Awesome Red Pen",
    "description": "The most awesome red pen you will ever see!",
    "price": 10
}

A cart item consists of:

• An ID
• A quantity
• A product ID
• A product name
• A product description
• A unit price
• A line total

{
    "id": 2,
    "quantity": 2,
    "name": "Awesome Red Pen",
    "description": "The most awesome red pen you will ever see!",
    "price": 10,
    "total": 20
}

#### Cart Item Events

• CartItemCreated
• CartItemQuantityUpdate
• CartItemDeleted

A cart consists of:

• An ID
• A collection of cart items
• A total

{
    "id": 3,
    "total": 20
}

POST to http://localhost:3000/carts/:cartID/items

{
  "id": 1,
  "quantity": 4
}

PUT to http://localhost:3000/carts/:cartID/items/9999

{
  "id": 1,
  "quantity": 4
}

GET to http://localhost:3000/carts/1/items