Add a rating handler proxy to Echo. A rating handler proxy allows clients to rate a service from $0$ to $5$ stars. Clients can rate a service with the command "rate $N"$ where $N$ is an integer between $0$ and $5.$ Clients can see the average rating using the command "rating".

For example, here's the terminal for SimpleClient #$1$:And here's the terminal for SimpleClient #$2$:Hints:

The same client may rate the service multiple times. $($Not ideal, but $...)$

The rating command returns the average of the total number of stars awarded since the server began running. $($Note that averages are doubles.$)$

Clients should not be allowed to update or access ratings simultaneously as this could lead to race condition.

Do not alter any existing Echo code.