Why gives an error (IndexError: string index out of range)

Code:

import os def get_ip_address(url): command = "host " + url process = os.popen(command) results = str(process.read()) marker = results.find('has address') + 12 return results[marker:].splitlines()[0] 

Mistake:

File "C: \ Users \ Karen \ Desktop \ PocketSploit \ modules \ ip_address.py", line 8, in get_ip_address
Return results [marker] .splitlines () [0]