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# How to Use Claude Code to Write and Debug Python – Real Python

**[Real Python](https://daily.dev/sources/rpython)** · 25 min read · 2 upvotes · 0 comments

## Summary

A hands-on tutorial walks through installing and configuring Claude Code, then using it to build a command-line contact manager in Python from scratch. It covers permission modes (manual, accept edits, plan, auto), writing a CLAUDE.md conventions file, plan-first workflows, reviewing diffs, generating tests with unittest, and committing with Git. A second half demonstrates using Claude Code to explore an unfamiliar codebase, find bugs (a TypeError crash on malformed CSV rows, concurrent write corruption, newline rendering issues, and silent empty-string acceptance), and fix them. Ends with troubleshooting tips and an FAQ on installation, cost, and safety.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://realpython.com/how-to-use-claude-code>

## Questions this post answers

### How do I stop Claude Code's DictReader from crashing on CSV rows with missing columns?

Pass restval="" to csv.DictReader instead of relying on its default of None. When a CSV row has fewer columns than the header, DictReader fills the missing fields with None by default, and calling len() or ljust() on that None value raises a TypeError when formatting a table. Setting restval="" fills missing fields with an empty string instead, letting the row render safely.

_Anyone hardening CSV-based CLI tools can compare fixes like this alongside other Python debugging writeups on daily.dev._

### What are the default permission modes in Claude Code and how do I cycle through them?

Claude Code cycles through four default permission modes with Shift+Tab: Manual (pauses for approval before every edit, command, or network request), Accept Edits (applies edits automatically for later review via git diff), Plan (researches and proposes changes without editing files), and Auto (runs actions it judges safe and blocks risky ones). Bypass permissions and dontAsk modes are also available via flags or settings.

_Developers weighing how much autonomy to grant an AI coding agent can track these workflow patterns on daily.dev._

### Does Claude Code require Node.js or a specific Python version to install?

No. Claude Code ships as a self-contained native binary with no Node.js, global npm packages, or version manager required, and it does not depend on any specific Python version. An older npm-based install path still exists, but the native binary is the recommended installation method. Using it does require a paid Anthropic plan (Pro, Max, or Team) or API billing through the Anthropic Console.

_Developers evaluating setup overhead for AI coding tools can compare installation requirements on daily.dev._

## Similar posts on daily.dev

- [Getting Started With Claude Code – Real Python](https://daily.dev/posts/getting-started-with-claude-code-real-python-cicd5aptg) · Real Python · 0 upvotes · 0 comments
- [How to Write a CLAUDE.md File for Claude Code – Real Python](https://daily.dev/posts/how-to-write-a-claude-md-file-for-claude-code-real-python-qmsfwtb2t) · Real Python · 2 upvotes · 0 comments
- [How to Write Robust Code with Claude Code](https://daily.dev/posts/how-to-write-robust-code-with-claude-code-3p8hw1qzc) · Towards Data Science · 1 upvotes · 0 comments
- [Using Claude Code More Intentionally](https://daily.dev/posts/using-claude-code-more-intentionally-mcd9koill) · Viget · 12 upvotes · 0 comments

---

Tags: [#python](https://daily.dev/tags/python), [#testing](https://daily.dev/tags/testing), [#ai-agents](https://daily.dev/tags/ai-agents), [#claude-code](https://daily.dev/tags/claude-code)

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