Reference library

Python Code Samples

Medium snippets you can copy, study, and run in the browser editor.

3 matches
Concurrency & performance medium

Limit Concurrency with asyncio.Semaphore in Python

Use asyncio.Semaphore to cap how many async tasks run at once, throttling a batch of coroutines to a set concurrency limit.

asyncio concurrency semaphore
Python 
import asyncio
import random


async def fetch_data(i: int, semaphore: asyncio.Semaphore) -> str:
    async with semaphore:
        print(f"Task {i} starts")
        await asyncio.sleep(random.uniform(0.1, 0.5))
        print(f"Task {i} finishes")
        return f"Result {i}"


async def main() -> None:
    semaphore …
13 0 Open
Caching & Redis medium

Redis-inspired sliding window rate limiter in Python

A pure-Python sliding window rate limiter using a deque of timestamps, mock-ready for Redis-backed production limits.

redis rate-limit sliding-window
Python 
import time
from collections import deque


class SlidingWindowRateLimiter:
    def __init__(self, max_requests: int, window_seconds: int) -> None:
        self.max_requests = max_requests
        self.window_seconds = window_seconds
        self.requests: dict[str, deque] = {}

    def is_allowed(self, client_id: str…
14 0 Open
Reliability & rate limiting medium

How to Implement a Token Bucket Rate Limiter per Client IP in Python

Implements a simple sliding-window rate limiter using a dictionary of timestamp lists per client IP to limit requests per window.

rate-limiting sliding-window ip
Python 
from time import time
from collections import defaultdict

class RateLimiter:
    def __init__(self, max_requests: int, window_seconds: int):
        self.max_requests = max_requests
        self.window_seconds = window_seconds
        self.clients = defaultdict(list)

    def allow(self, ip: str) -> bool:
        now…
13 0 Open

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Copy-ready Python snippets for learners and developers

PythonSkillset code samples are short, focused examples organised by topic and difficulty. Every snippet is server-rendered HTML — readable by search engines and easy to copy. Open any sample, read the notes, copy the code, then press Try in editor to run it in the browser with Pyodide.

How to use this library

  1. Pick a topic section — strings, lists, files, functions, and more
  2. Open a sample, read How it works, and copy the code block
  3. Run it in the IDE, tweak values, then take a related quiz or tutorial lesson

Samples vs tutorials and challenges

Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.

Related coding tools

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