Implements a lightweight, framework-agnostic event emitter service for decoupled internal communication. Allows services to subscribe to and emit events without direct dependencies, promoting loose coupling and testability. Self-contained with only standard library and typing imports, making it highly reusable in any Python async application.

Provides a simple yet effective caching utility with time-to-live (TTL) support. Offers both decorator and class-based interfaces for caching function results or arbitrary values. Thread-safe for single-process use, zero external dependencies beyond standard library, and easily adaptable to different caching backends. Demonstrates clean separation of concerns and minimal coupling.

Delivers generic pagination utilities using Pydantic models for request/response validation. Includes helper functions to paginate query results and generate pagination metadata. Decoupled from specific ORMs and data sources, requiring only slicing and counting capabilities. Shows strong use of Python generics and type safety for reusable data access patterns.

Contains essential security utilities including secure password hashing (HMAC-SHA256), token generation, and request signature verification. All functions are self-contained, rely only on standard library, and follow cryptographic best practices. Represents a reusable security toolkit applicable to various projects needing basic authentication and data protection mechanisms.

Implements an asynchronous retry queue with exponential backoff and jitter for handling transient external API failures. Manages a queue of failed requests and automatically retries with increasing delays, reducing impact of temporary outages. Designed as a generic service adaptable to any external integration, showcasing resilience patterns and async queue management.