Python Docs

Python Expert (3.13)

Official Documentation: https://docs.python.org/3/

Quick Reference

| Topic | File | |-------|------| | Variables, built-in types, strings, bytes/bytearray/memoryview, control flow, f-strings, pattern matching, keywords, constants, special attributes, dict views, set methods | basics-syntax.md | | Functions, lambda, args/*kwargs, decorators, generators, closures, scope resolution (LEGB) | functions-lambdas.md | | Classes, inheritance, dataclasses, enums, metaclasses, properties, slots, dunder methods | classes-objects.md | | List, dict, set, tuple, comprehensions, collections module, sequences | collections.md | | Imports, packages, pip, venv, pyproject.toml, packaging, distribution | modules-packages.md | | try/except, custom exceptions, exception groups, context managers, warnings | exceptions.md | | Type hints, generics, protocols, TypedDict, mypy, pyright, narrowing | typing.md | | async/await, asyncio, tasks, streams, synchronization, async generators | async-asyncio.md | | os, sys, math, itertools, functools, datetime, json, re, argparse, random | stdlib-core.md | | File I/O, pathlib, io, csv, pickle, logging, shutil, tempfile | stdlib-io.md | | threading, multiprocessing, concurrent.futures, queue, socket, ssl, http, socketserver, sqlite3, hashlib/hmac, base64, struct, decimal, fractions, statistics, time, inspect, traceback, gc, weakref, types, operator, zipfile/tarfile, configparser, tomllib, ipaddress, urllib, ctypes, email/smtplib/imaplib/poplib, html.parser/entities, xml.etree/dom/sax/expat, string, textwrap, difflib, unicodedata, codecs, numbers, pdb, cProfile, timeit, tracemalloc, faulthandler, atexit, signal, mmap, sched, tkinter, turtle, curses, gettext/locale, copyreg, pkgutil, importlib, contextvars, graphlib, zoneinfo, calendar, pprint, cmath, logging.config/handlers, select/selectors, stat, reprlib, filecmp, fileinput, cmd, readline, rlcompleter, stringprep, netrc, plistlib, mailbox, binascii, quopri, wsgiref, ftplib, http.cookies/cookiejar, xmlrpc, wave, colorsys, bdb, trace, sys.monitoring, code/codeop, modulefinder, zipimport, optparse, thread, sharedmemory, builtins, warnings, os.path, audit events, devmode, IDLE, test, dis, py_compile, compileall, tokenize, tabnanny, symtable, keyword, ast, removed modules (imghdr, sndhdr, crypt, aifc, sunau, chunk, nntplib, telnetlib, uu, xdrlib, cgi, cgitb, distutils, formatter), descriptors, GIL | stdlib-extended.md | | pytest, unittest, mocking, fixtures, coverage, hypothesis, doctest | testing.md | | PEP 8, idioms, patterns, performance, EAFP, duck typing, naming | idioms-best-practices.md | | Python 3.13 features, free-threaded, JIT, REPL, error messages, 3.12/3.11 changes | whats-new.md |

Core Philosophy

Python is a high-level, dynamically typed, multi-paradigm programming language. Key principles:

1. Readability — clean syntax, significant indentation, "batteries included" stdlib
2. Dynamic Typing — types checked at runtime, duck typing, optional static type hints
3. Multi-paradigm — OOP, functional, procedural, imperative styles all supported
4. Interpreted — no compilation step, interactive REPL, rapid development
5. Batteries Included — comprehensive standard library out of the box
6. Async — async/await with asyncio for concurrent I/O-bound code
7. Extensible — C FFI, C extensions, ctypes, cffi, rich package ecosystem

Hello World

print("Hello, World!")

# With command-line args
import sys
print(f"Args: {sys.argv}")

Variables

# Dynamic typing — no declaration needed
x = 42          # int
x = "hello"     # now str — variables can change type
x = [1, 2, 3]   # now list

# Multiple assignment
a, b, c = 1, 2, 3

# Swap
a, b = b, a

# Unpacking
first, *rest = [1, 2, 3, 4]  # first=1, rest=[2, 3, 4]

Built-in Types Quick Reference

| Category | Types | Example | |----------|-------|---------| | Numbers | int, float, complex | x = 42 | | Boolean | bool | flag = True | | Text | str | s = "hello" | | Sequences | list, tuple, range | lst = [1, 2, 3] | | Sets | set, frozenset | s = {1, 2, 3} | | Mappings | dict | d = {"key": "value"} | | None | NoneType | x = None | | Binary | bytes, bytearray | b = b"data" |

Operators

| Operator | Description | |----------|-------------| | + - * / // % ** | Arithmetic (floor div, modulo, power) | | += -= *= /= //= %= **= | Augmented assignment | | == != ` = | Comparison | | and or not | Boolean (short-circuit) | | in not in | Membership | | is is not | Identity | | & \| ^ ~ > | Bitwise | | :=` | Walrus operator (assignment expression) |

Control Flow Quick Reference

# if/elif/else
if x > 0:
    print("positive")
elif x = 0 else "error"

# for loop
for item in [1, 2, 3]:
    print(item)

for i in range(5):
    print(i)

# while
while condition:
    do_something()

# match (pattern matching, Python 3.10+)
match command:
    case "quit":
        exit()
    case "go" | "move":
        move()
    case _:
        print("unknown")

Functions Quick Reference

# Basic function
def add(a, b):
    return a + b

# Default parameters
def greet(name, greeting="Hello"):
    return f"{greeting}, {name}!"

# *args and **kwargs
def func(*args, **kwargs):
    print(args)    # tuple
    print(kwargs)  # dict

# Lambda
square = lambda x: x * x

# Generator
def count_up(n):
    i = 0
    while i < n:
        yield i
        i += 1

Classes Quick Reference

# Basic class
class Dog:
    def __init__(self, name):
        self.name = name

    def bark(self):
        return f"{self.name} says woof!"

# Dataclass (auto-generates __init__, __repr__, __eq__)
from dataclasses import dataclass

@dataclass
class User:
    id: int
    name: str
    email: str

# Enum
from enum import Enum

class Color(Enum):
    RED = 1
    GREEN = 2
    BLUE = 3

Async Quick Reference

import asyncio

async def fetch_data():
    await asyncio.sleep(1)
    return "data"

async def main():
    result = await fetch_data()
    print(result)

asyncio.run(main())

Installation & Setup

# Check version
python --version

# Create virtual environment
python -m venv .venv

# Activate (Linux/macOS)
source .venv/bin/activate

# Activate (Windows)
.venv\Scripts\activate

# Install packages
pip install package_name
pip install -r requirements.txt

# Run a script
python script.py

# Interactive REPL (improved in 3.13)
python

Project Creation

# Simple project
mkdir myproject && cd myproject
python -m venv .venv
source .venv/bin/activate
pip install -e .

# With pyproject.toml (modern)
# Use: uv init, poetry new, or hatch new
uv init myproject
cd myproject
uv sync

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [pledgeandgrow](https://github.com/pledgeandgrow)
- **Source:** [pledgeandgrow/pledge-skills](https://github.com/pledgeandgrow/pledge-skills)
- **License:** MIT

Install and usage instructions live in the source repository linked above.