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Copy-ready Python snippets by topic and difficulty — short, focused, and runnable in the browser editor.
How to Explain SQLite Query Plans in Python
Build a Python function that runs EXPLAIN QUERY PLAN on SQLite in-memory tables and prints the optimizer's execution plan for any SELECT statement.
import sqlite3
def explain_query(sql: str) -> str:
"""Return the SQLite query plan for the given SQL statement."""
conn = sqlite3.connect(":memory:")
cursor = conn.cursor()
# Create sample data for a realistic plan
cursor.execute("CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT)")
c…How to Insert a Mock Route Record Using SQLite in Python
This code creates an in-memory SQLite table for routes and inserts a mock route record, returning the inserted row for verification.
import sqlite3
from datetime import datetime
def insert_mock_record(db_path=":memory:"):
conn = sqlite3.connect(db_path)
cursor = conn.cursor()
cursor.execute("""
CREATE TABLE IF NOT EXISTS routes (
id INTEGER PRIMARY KEY AUTOINCREMENT,
origin TEXT NOT NULL,
des…Offset vs Keyset Pagination in Python
Demonstrate offset-based pagination and keyset (cursor) pagination with a simple in-memory dataset, showing how each returns pages of records.
"""Demonstrate pagination using offset vs keyset (cursor) approach."""
ITEMS = [
{"id": 1, "name": "Alice"},
{"id": 2, "name": "Bob"},
{"id": 3, "name": "Carol"},
{"id": 4, "name": "David"},
{"id": 5, "name": "Eve"},
]
def offset_paginate(items, page, page_size):
"""Return a page using offset…Snowflake ID Generator with Cluster Index Mock in Python
A thread-safe Snowflake ID generator mock that creates unique 64-bit IDs across simulated cluster nodes and maintains a sorted in-memory index for range queries.
import time
import threading
class SnowflakeIDGenerator:
def __init__(self, machine_id, datacenter_id):
self.machine_id = machine_id
self.datacenter_id = datacenter_id
self.sequence = 0
self.last_timestamp = -1
self.machine_bits = 5
self.datacenter_bits = 5
…Fetch Secrets from a Mock Secrets Manager in Python
Build a minimal in-memory secrets manager that stores and retrieves secret values, raising a KeyError for missing names.
import json
class SecretsManager:
"""Mock secrets manager that returns secrets from a local store."""
def __init__(self, store=None):
self.store = store or {
"api_key": "mock-api-key-123",
"db_password": "s3cret-p@ss",
"jwt_secret": "dev-only-secret"
}
…How to Mock a Redis Session Store in Python
An in-memory RedisSessionStore class with TTL-based expiry, get/set/delete/exists methods, and JSON field support—perfect for testing and prototyping without a live Redis.
import time
import json
from collections import defaultdict
class RedisSessionStore:
"""In-memory mock of a Redis-backed session store."""
def __init__(self, ttl=3600):
self._data = defaultdict(dict)
self._expires = {}
self._ttl = ttl
def set(self, session_id, field, value):
…How to Mock a Container Registry in Python
Build an in-memory container registry mock with push, tag listing, and manifest retrieval logic for testing deployment tooling.
import json
from collections import defaultdict
class MockRegistry:
def __init__(self):
self.repositories = defaultdict(dict)
def push_image(self, repo: str, tag: str, layers: list[str]) -> None:
self.repositories[repo][tag] = {
"layers": layers,
"size": sum(len(layer…Browse by section
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Guide: free Python code samples library
Copy-ready Python snippets for learners and developers
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- 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.