How to implement rate limiting per API key in Python

import time

API_RATE_LIMITS = {"api_key_1": 5, "api_key_2": 3}  # max requests per window
WINDOW_SECONDS = 10

class RateLimiter:
    def __init__(self, limits, window):
        self.limits = limits
        self.window = window
        self.requests = {key: [] for key in limits}

    def allow(self, api_key):
        now = time.time()
        timestamps = self.requests.setdefault(api_key, [])
        # Remove old timestamps outside the window
        timestamps[:] = [t for t in timestamps if now - t < self.window]
        if len(timestamps) >= self.limits.get(api_key, 0):
            return False
        timestamps.append(now)
        return True

if __name__ == "__main__":
    limiter = RateLimiter(API_RATE_LIMITS, WINDOW_SECONDS)
    for key in ["api_key_1", "api_key_2", "unknown_key"]:
        results = [limiter.allow(key) for _ in range(6)]
        print(f"{key}: {results}")