What problem does it solve? Python developers often reinvent solutions or fall into common anti-patterns when building APIs, data pipelines, tests, or CLI tools. This Skill provides a curated index of battle-tested pattern references so the AI applies correct, idiomatic Python practices immediately instead of generating generic or outdated code. ## Core Features & Use Cases - FastAPI Patterns: App factory with lifespan, Pydantic v2 schemas, dependency injection, error handling, and BaseSettings configuration. - Data Transformation: Decision guidance for pandas vs polars, vectorized operations, lazy pipelines, and efficient group-by/join patterns. - Testing & Packaging: pytest fixtures, mocking, parametrize, coverage configuration, plus modern pyproject.toml packaging and PyPI publishing. - Async & CLI: asyncio gather, queues, semaphores, executors, plus argparse/Typer/Rich CLI patterns with semantic exit codes. - Use Case: When asked to build a REST endpoint that fetches data concurrently, the Skill directs the AI to the FastAPI and asyncio references, producing typed, tested code that avoids blocking the event loop. ## Quick Start Use the python skill to review my FastAPI endpoint and apply the correct async and Pydantic v2 patterns.