Docstrings

Basic Docstrings Use triple quotes for docstrings. A simple docstring is a single line that describes what the function does: Multi-line Docstrings For functions with parameters, return values, or complex behavior, use a multi-line docstring that documents the interface completely: This multiline docstring format provides everything a user needs: a summary, detailed description, parameter documentation, return value, exceptions, and usage examples. Docstring Structure A well-structured docstring contains several key components that make it comprehensive and useful. Docstring Best Practices The difference between a helpful docstring and a useless one comes down to specificity and completeness. Write docstrings for any function that will be used by others or that you might return to later. T

About This Interactive Section

This section is part of the Functional Programming: Intermediate lesson on DataDriven, a free data engineering interview prep platform. Each section includes explanations, worked examples, and hands-on code challenges that execute in real time. SQL queries run against a live PostgreSQL database. Python runs in a sandboxed Docker container. Data modeling problems validate against interactive schema canvases. All content is framed around what data engineering interviewers actually test at companies like Meta, Google, Amazon, Netflix, Stripe, and Databricks.

How DataDriven Lessons Work

DataDriven combines four interview rounds (SQL, Python, Data Modeling, Pipeline Architecture) with adaptive difficulty and spaced repetition. Easy problems get harder as you improve. Weak concepts resurface until you master them. Your readiness score tracks progress across every topic interviewers test. Every lesson section ends with problems you solve by writing and running real code, not by picking multiple-choice answers.