This is an express HTTP server in Node.js which will handle the logic of a todo
  list app.

  Each todo has a title and a description. The title is a string and the description is 
  a string.

  Each todo also gets an unique autogenerated id every time it is created
  The API endpoints are defined below,

  1.GET /todos - Retrieve all todo items
    Description: Returns a list of all todo items.
    Response: 200 OK with an array of todo items in JSON format.
    Example: GET http://localhost:3000/todos
    
  2.GET /todos/:id - Retrieve a specific todo item by ID
    Description: Returns a specific todo item identified by its ID.
    Response: 200 OK with the todo item in JSON format if found, or 404 Not Found if 
    not found.
    Example: GET http://localhost:3000/todos/123
    
  3. POST /todos - Create a new todo item
    Description: Creates a new todo item.
    Request Body: JSON object representing the todo item.
    Response: 201 Created with the ID of the created todo item in JSON format. eg: {id: 1}
    Example: POST http://localhost:3000/todos
    Request Body: { "title": "Buy groceries", "completed": false, description: "I should
     buy groceries" }
    
  4. PUT /todos/:id - Update an existing todo item by ID
    Description: Updates an existing todo item identified by its ID.
    Request Body: JSON object representing the updated todo item.
    Response: 200 OK if the todo item was found and updated, or 404 Not Found if not
     found.
    Example: PUT http://localhost:3000/todos/123
    Request Body: { "title": "Buy groceries", "completed": true }
    
  5. DELETE /todos/:id - Delete a todo item by ID
    Description: Deletes a todo item identified by its ID.
    Response: 200 OK if the todo item was found and deleted, or 404 Not Found if not found.
    Example: DELETE http://localhost:3000/todos/123

    - For any other route not defined in the server returns 404