Python 3.6+ wait until helper

wait.py

import time
import requests


class TimeoutException(Exception):

    def __init__(self, message):
        self.message = message

    def __str__(self):
        return repr(self.message)


def wait_until(callback, timeout=10, poll_frequency=0.5, message=None):
    end_time = time.time() + timeout
    while True:
        try:
            result = callback()
        except Exception:
            result = False
        if result:
            return result
        time.sleep(poll_frequency)
        if time.time() > end_time:
            break
    if message is None:
        condition_name = callback.__class__.__name__
        message = f'The condition {condition_name} is not reached within {timeout} second(s)'
    raise TimeoutException(message)


# Callback example:

class status_code_is_200:

    def __init__(self, url):
        self.url = url

    def __call__(self):
        response = requests.get(self.url)
        if response.status_code == 200:
            return response
        else:
            return False


# Usage example:

result = wait_until(
    status_code_is_200('https://google.com/'),
    timeout=5,
    poll_frequency=0.1,
    message='resource is not available!'
)