Python Code
Samples
Medium snippets you can copy, study, and run in the browser editor.
Distributed tracing with contextvars in Python
Propagate trace and span IDs across function calls using contextvars to mock distributed tracing in a single process.
import contextvars
import uuid
import time
_trace_context = contextvars.ContextVar("trace_context", default=None)
class TraceContext:
def __init__(self, trace_id, parent_span_id):
self.trace_id = trace_id
self.parent_span_id = parent_span_id
self.span_id = uuid.uuid4().hex[:16]
s…How to Handle mTLS Certificate Rotation in Python
Detect mTLS certificate file changes by tracking modification time and hot-reload the SSL context in a running service.
import ssl
import tempfile
import datetime
from pathlib import Path
class MTLSContext:
def __init__(self, cert_path, key_path, ca_path):
self.cert_path = Path(cert_path)
self.key_path = Path(key_path)
self.ca_path = Path(ca_path)
self.context = None
self.last_loaded_mtime …How to simulate a contextual bandit in Python
Simulate a contextual multi-armed bandit with random features and epsilon-greedy action selection in Python.
import random
class ContextualBandit:
def __init__(self, n_actions=3, n_features=4):
self.n_actions = n_actions
self.n_features = n_features
self.theta = [random.random() for _ in range(n_actions * n_features)]
def mock_context(self):
return [random.uniform(-1, 1) for _ in ra…Build a Full Text Search Index in Python
Create a simple inverted index for full-text search with the standard library, supporting multi-word AND queries across documents.
import re
from collections import defaultdict
class SimpleTextIndex:
def __init__(self):
self.index = defaultdict(list)
self.documents = {}
def add_document(self, doc_id, text):
self.documents[doc_id] = text
words = set(re.findall(r'\w+', text.lower()))
for word in wo…Database Helper in Python with SQLite Scaling Optimization
Build a beginner-friendly SQLite database helper class with WAL, indexed queries, and efficient batch inserts for scaling.
import sqlite3
from contextlib import contextmanager
class DatabaseHelper:
"""Beginner-friendly helper for SQLite database operations with scaling tips."""
def __init__(self, db_path):
self.db_path = db_path
@contextmanager
def connection(self):
"""Context manager for automatic comm…How to Build a Connection Pool Reuse Mock in Python
Build a mock connection pool with context manager to track connection reuse, acquires, and releases in Python.
import time
from contextlib import contextmanager
class Connection:
def __init__(self, name):
self.name = name
self.in_use = False
self.busy_since = None
def fetch(self):
return f"data from {self.name}"
class ConnectionPool:
def __init__(self, size=3):
self.conn…How to Mock Environment Variables in Python
A context manager that injects and restores environment variables for isolated testing of config-dependent code.
import os
class EnvInjector:
def __init__(self, mock_vars=None):
self.mock_vars = mock_vars or {}
self.original = {}
def __enter__(self):
for key, value in self.mock_vars.items():
if key in os.environ:
self.original[key] = os.environ[key]
os.env…How to Mock an mTLS Client Certificate in Python
Create a self-signed client certificate and key with OpenSSL, load them into an SSL context, and simulate an mTLS handshake in Python for testing.
import ssl
import socket
import subprocess
import tempfile
from pathlib import Path
def create_mock_certificates():
"""Generate self-signed client certificate and key for mTLS testing."""
with tempfile.TemporaryDirectory() as tmpdir:
cert_path = Path(tmpdir) / "client.crt"
key_path = Path(tmpd…Browse by section
Each section groups closely related Python snippets.
Guide: free Python code samples library
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
- Pick a topic section — strings, lists, files, functions, and more
- Open a sample, read How it works, and copy the code block
- 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.