Provides a generic AsyncRateLimiter class that limits the rate of asynchronous function invocations. It accepts a duration and an optional backlog limit, ensuring that calls are spaced out or dropped if the queue is full. This utility is self-contained (no internal imports beyond dart:async) and can be extracted into any Dart project needing rate-limited async operations.

Implements the Single Flight pattern for Dart async operations: given a key and an async function, it ensures only one outstanding call per key at a time, sharing the result with concurrent callers. The implementation is test-covered, thread-safe, and has no internal dependencies beyond dart:async. It can be reused in any Dart project to deduplicate expensive async operations.

Provides an AsyncSerialQueue class that serializes asynchronous operations, ensuring they execute in FIFO order sequentially. It uses a simple queue and future chaining, with no external dependencies. This is a standalone utility suitable for any Dart project that needs to avoid concurrent execution of state-mutating operations.

Implements a custom M3U8 playlist parser that handles both master and media playlists, including hierarchical segment resolution, EXT-X-KEY extraction, and DISCONTINUITY handling. The parser is test-covered, has no external HTTP dependencies (it works on string input), and can be extracted into any Dart project needing client-side HLS playlist analysis or ad filtering.