Sliding window rate limiter

Implement a sliding-window rate limiter. Given a chronologically-ordered list of events [key, timestamp], a window size in seconds, and a 'limit' (max allowed events per key within any window), return the list of booleans indicating, for each event in order, whether it is ALLOWED. An event is allowed if the count of previously-allowed events for the same key whose timestamp is strictly greater than (timestamp - window) is less than 'limit'; allowed events are recorded, rejected events are not. Timestamps are non-decreasing.