How to implement rate limiting in Python

import time

class RateLimiter:
    def __init__(self, max_calls, period):
        self.max_calls = max_calls
        self.period = period
        self.calls = []
    
    def allow(self):
        now = time.time()
        # Remove calls older than the period window
        self.calls = [t for t in self.calls if now - t < self.period]
        if len(self.calls) < self.max_calls:
            self.calls.append(now)
            return True
        return False
    
    def wait_time(self):
        if self.allow():
            return 0
        now = time.time()
        self.calls = [t for t in self.calls if now - t < self.period]
        if not self.calls:
            return 0
        return round(self.period - (now - min(self.calls)), 2)


def format_data(data, limiter):
    """
    Format a list of items with a timestamp,
    respecting the rate limit.
    """
    results = []
    for item in data:
        if limiter.allow():
            results.append(f"[{time.strftime('%H:%M:%S')}] {item}")
        else:
            results.append(f"[Rate limited] {item} (wait {limiter.wait_time()}s)")
    return "\n".join(results)


if __name__ == "__main__":
    # Allow 3 calls per 5-second window
    limiter = RateLimiter(max_calls=3, period=5)
    sample_data = ["apple", "banana", "cherry", "date", "elderberry", "fig"]
    
    output = format_data(sample_data, limiter)
    print(output)