How do I read the event stream in Python?

import json, requests

def follow(run_id):
    after = 0
    while True:
        with requests.get(f"{BASE}/v1/runs/{run_id}/events",
                          params={"after": after}, headers=headers, stream=True) as r:
            event = None
            for line in r.iter_lines(decode_unicode=True):
                if line.startswith("event: "):
                    event = line[7:]
                elif line.startswith("data: "):
                    data = json.loads(line[6:])
                    if event == "step":
                        after = data["index"] + 1
                        print(data)
                    elif event == "done":
                        return data
        # timeout or dropped connection: loop and reconnect

This is the client from the Streaming guide.