Backup Cisco Switch and Router Configuration using telnet with Python

import sys
import getpass
import telnetlib
import time
from datetime import date
from datetime import datetime
import os


def get_filename_datetime():
    # Use current date & time to get a text file name.
    return str(datetime.now().strftime('%Y_%m_%d %H_%M_%S'))

# Get full path for writing.
fname = get_filename_datetime()

user = input("Enter your remote  telnet account: ")
password = getpass.getpass()

with  open("switchlist.txt") as file:

   for ip in file:
       HOST = ip.strip()
       
   #Removed Space of any at the end of IP address.
       try:
            tn = telnetlib.Telnet(HOST)
      #print("trying to connect a host" + " "  +HOST)
       except:
            print("\x1b[0;31;40m" + "Error to connect"  + " " +HOST +"\x1b[0m")
      #If Telnet failed to device due to some reason then show error and continue to next hop this Error will be highlighted.
            continue

       tn.read_until(b"Username: ")
       tn.write(user.encode('ascii') + b"\n")
       if password:
           tn.read_until(b"Password: ")
           tn.write(password.encode('ascii') + b"\n")
           tn.write(b'\r') 
       n, match, previous_text = tn.expect([br'Login invalid', br'\$'], 10)
       if n == 0:
           print("Username and password failed - giving up" + " "  +HOST)
       else:
          print("Login into the device and trying for backup on " + " "  +HOST)
          tn.write(b"terminal len 0\n")
          tn.write(b"show run\n")
          tn.write(b"exit\n")
       

          backupread=tn.read_all().decode('ascii')
          saveoutput=open("backup" + " " +HOST + " " +fname + ".txt", "w")
          saveoutput.write(backupread)
          saveoutput.close()
          print(" Backup Successfully " + " "  +HOST)