CQRS booking kata

Source: https://codingdojo.org/kata/CQRS_Booking/

Goal

We want to make a booking solution for one hotel.

The first 2 users stories are:

As a user I want to see all free rooms.
As a user I want to book a room.

They want to use the CQRS pattern. To do that, we will:

have one command service with a function called bookARoom(Booking)
call the WriteRegistry
notify the ReadRegistry called by the query service with the function: freeRooms(arrival: Date, departure: Date): Room[]

The Booking struct contains:

client id
room name
arrival date
departure date

And the Room struct contains only:

room name