QUIT
Syntax
QUIT
Time complexity: O(1)
Ask the server to close the connection. The connection is closed as soon as all pending replies have been written to the client.
Note: Clients should not use this command.
Instead, clients should simply close the connection when they're not used anymore.
Terminating a connection on the client side is preferable, as it eliminates TIME_WAIT
lingering sockets on the server side.
Return
Simple string reply: always OK.