title: Check if User input correct ipv4 format
body: <p>My first time here, i have a question please:</p>
  
  <p>i want to check if user type on input an ipv4 if it's not ipv4 user should receive error 3 times and then exit. My example code below:</p>
  
  <pre><code>    # Hosts and Commands
      for attempt in range(3):
          host = input("Enter IPs separated by SPACE: ")
          cmd = input("Enter Command(s) seperated by ',' : ")
          if(len(host) != 0) and (len(cmd) != 0):
              break
          print("Fields Cannot be Blank, try again...")
      else:
          Screen().input("Sorry...Execution Terminated, Press [ENTER] to Exit")
          return
  </code></pre>