is_allowed.py

def is_allowed(key:str) -> Bool:
    """The function decides is the current request should be served or not.
    It accepts the configuration key `key` and checks the number of requests made against it
    as per the configuration.
    The function returns True if the request goes through and False otherwise.
    """
    current_time = int(time.time())

    # Fetch the configuration for the given key
    # the configuration holds the number of requests allowed in a time window.
    config = get_ratelimit_config(key)

    # Fetch the current window for the key
    # The window returned, holds the number of requests served since the start_time
    # provided as the argument.
    start_time = current_time - config.time_window_sec
    window = get_current_window(key, start_time)

    if window.number_of_requests > config.capacity:
        return False
    
    # Since the request goes through, register it.
    register_request(key, current_time)

    return True