Modules & Packages

Split code into modules and reuse third‑party packages.

import math
from pathlib import Path

def area(r):
    return math.pi * r ** 2

Create virtual environments and install packages:

python -m venv .venv
source .venv/bin/activate
pip install requests

C# groups code with namespaces and NuGet packages; JavaScript uses ES modules and npm.

Practice Questions

1. Which command activates a virtual environment on Unix-like systems?
   Answer

   `source .venv/bin/activate`.
2. What is the JavaScript equivalent of Python’s import?
   Answer

   `import` statements for ES modules.