May you help me implement the following in my code:

$-$ Allow Client to leave the system by implementing a command. Use the username

passed to client.py to print $[$username$]$ has left$$ on all other connected Clients.

$-$ Allow Client to leave the system unexpectedly. Use the username passed to client.py

to print $[$username$]$ has left$$ on all other connected Clients

$-$ One of the connected clients disconnecting should not cause the server to crash

$-$ Client should be able to unicast messages to another client individually when there

are more than two clients in the system. They also should be able to change between broadcast and unicast

$-$ In case of a crash, attempt to close remaining connections and print an error messagein the terminals of all previous connected devices.

my code :

server.py:

import socket

import threading

import sys

def main$($port$)$:

host $=$ 'localhost'

server $=$ socket.socket$($socket$.$AF$\_$INET, socket.SOCK$\_$STREAM$)$

server.bind$(($host$,$ port$))$

server.listen$()$

clients $=[]$

usernames$=[]$

def broadcast$($message$,$ sender$\_$client$=$None$)$:

for client in clients:

if client $!=$ sender$\_$client:

client.send$($message$)$

def handle$\_$client$($client$)$:

while True:

try:

message $=$client.recv$(1024)$

broadcast$($message$,$client$)$

except:

index $=$ clients.index$($client$)$

clients.remove$($client$)$

client.close$()$

username $=$ usernames$[$index$]$

broadcast$($f$\text{'}\{$username$\}$ has left'.encode$())$

usernames.remove$($username$)$

break

def receive$\_$client$()$:

while True:

client, address $=$ server.accept$()$

print$($f$"$Connection coming from $\{$str$($address$)\}")$

client.send$(\text{'}$Username$\text{'}.$encode$())$

username $=$ client.recv$(1024).$decode$()$

usernames.append$($username$)$

clients.append$($client$)$

print$($f$\text{'}\{$username$\}$ has joined'$)$

broadcast$($f$"\{$username$\}$ has joined".encode$())$

client.send$(\text{'}$Welcome to the server'.encode$())$

thread $=$ threading.Thread$($target$=$ handle$\_$client $,$ args$=($client$,))$

thread.start$()$

receive$\_$client$()$

if $\_\_$name$\_\_=="\_\_$main$\_\_"$:

if len$($sys$.$argv$)<1$:

print$("$Usage: python$3$ server.py $[$port$]")$

else:

main$($int$($sys$.$argv$[1]))$

client.py:

import socket

import threading

import sys

def main$($username$,$ hostname, port$)$:

client $=$ socket.socket$($socket$.$AF$\_$INET, socket.SOCK$\_$STREAM$)$

try:

client.connect$(($hostname$,$ port$))$

except Exception as e:

print$($f$"$Could not connect: $\{$e$\}")$

def receive$\_$mesage$()$:

while True:

try:

message $=$ client.recv$(1024).$decode$()$

if message $==$ 'Username':

client.send$($username$.$encode$())$

else:

print$($message$)$

except Exception as e:

print$($f$"$Error: $\{$e$\}")$

client.close$()$

break

def write$()$:

while True:

message $=$ f$\text{'}\{$username$\}$: $\{$input$("")\}\text{'}$

if message $==$ "command":

command $=$ input$($f$\text{'}\{$username$\}$command $>\text{'})$

if command $=="/$exit$"$:

client.send$("/$exit$".$encode$())$

break

elif command.startswith$("/$broadcast$")$:

client.send$($command$.$encode$())$

elif command.startswith$("/$unicast$")$:

client.send$($command$.$encode$())$

elif command $=="/$files$"$:

client.send$("/$files$".$encode$())$

elif command.startswith$("/$download$")$:

client.send$($command$.$encode$())$

else:

print$("$Invalid command."$)$

client.close$()$

else:

client.send$($message$.$encode$())$

receive$\_$thread $=$ threading.Thread$($target$=$ receive$\_$mesage$)$

receive$\_$thread.start$()$

write$\_$thread $=$ threading.Thread$($target$=$ write$)$

write$\_$thread.start$()$

if $\_\_$name$\_\_=="\_\_$main$\_\_"$:

if len$($sys$.$argv$)<4$:

print$("$Usage: python client.py $[$username$][$hostname$][$port$]")$

else:

main$($sys$.$argv$[1],$ sys$.$argv$[2],$ int$($sys$.$argv$[3]))$