Python Fundamentals (Modern Python 3.12+)

# Types are inferred but you can annotate
name: str = "Alex"
age: int = 30
active: bool = True
scores: list[int] = [85, 92, 78]   # Python 3.9+, no need for List from typing

# f-strings (always use these)
print(f"{name} is {age}")
print(f"{age=}")               # 3.8+ debug form: outputs 'age=30'

# Walrus operator (3.8+)
if (n := len(scores)) > 0:
    print(f"{n} scores")

# Match (3.10+), like switch but real pattern matching
def classify(value):
    match value:
        case int() if value > 100: return "big int"
        case int(): return "int"
        case [first, *rest]: return f"list starting with {first}"
        case {"name": name}: return f"dict with name {name}"
        case _: return "other"

# Functions with type hints + defaults
def greet(name: str, greeting: str = "Hello") -> str:
    return f"{greeting}, {name}"

# Keyword-only args (after *)
def build_user(name: str, *, email: str, admin: bool = False) -> dict:
    return {"name": name, "email": email, "admin": admin}

# Imports: prefer explicit
from datetime import datetime
import json  # standard library
from mypackage.users import get_user  # your package