Check if someone is online on steam in python 3

steamcheck.py

import urllib.request
import json
import sys

def isOnline(api_key, steam_id): #Steam ID is the 64bit one
    req_headers = {'User-Agent': 'Python script'}
    url = "http://api.steampowered.com/ISteamUser/GetPlayerSummaries/v0002/?key=" + api_key + "&steamids=" + steam_id + "&format=json"
    req = urllib.request.Request(url, data=None, headers=req_headers, origin_req_host=None)
    response = urllib.request.urlopen(req)
    content = response.read()
    data = json.loads(content.decode('utf8'))
    if data["response"]["players"][0]["personastate"] == 0: #0 = offline
        return False 
    elif data["response"]["players"][0]["personastate"] == 1 or data["response"]["players"][0]["personastate"] == 2 or data["response"]["players"][0]["personastate"] == 3: #1 = online, 2 = busy, 3 = away
        return True
    else:
        print("Error: Unknown persona state")
        input("Press enter to continue...")
        sys.exit()

how do i use it?