--- title: "Real Dev (@realdev9868) | Hashnode" description: "Free interactive coding practice for students and developers. SQL, DSA, Python and more. From the Schoolabe team." url: "https://hashnode.com/@realdev9868" --- @realdev9868 # Real Dev @realdev9868 · Joined October 2026 Free interactive coding practice for students and developers. SQL, DSA, Python and more. From the Schoolabe team. [Website](https://www.schoolabe.com/) ### [Python's mutable default argument bug, run one call at a time](https://realdev9868.hashnode.dev/python-s-mutable-default-argument-bug-run-one-call-at-a-time?utm_source=hashnode&utm_medium=feed) Why a list default keeps growing between calls, how to see it with \_\_defaults\_\_, the None fix, and two places the same bug hides. 6 min read · [realdev9868.hashnode.dev](https://realdev9868.hashnode.dev/python-s-mutable-default-argument-bug-run-one-call-at-a-time?utm_source=hashnode&utm_medium=feed) [Oct 27](https://hashnode.com/posts/python-s-mutable-default-argument-bug-run-one-call-at-a-time/6ae017fdb9edb22e5287a6eb) ### [The Python Copy Bug That Looks Fine in Code Review](https://realdev9868.hashnode.dev/the-python-copy-bug-that-looks-fine-in-code-review?utm_source=hashnode&utm_medium=feed) A shallow copy, a shared inner list, and a deepcopy fix, with every snippet run on Python 3.13 and the real output pasted. 6 min read · [realdev9868.hashnode.dev](https://realdev9868.hashnode.dev/the-python-copy-bug-that-looks-fine-in-code-review?utm_source=hashnode&utm_medium=feed) [Oct 20](https://hashnode.com/posts/the-python-copy-bug-that-looks-fine-in-code-review/6ad6e570665835984f0dd41a) ### [Pandas Basics on a Real Dataset: A Hands-On Walkthrough with Palmer Penguins](https://realdev9868.hashnode.dev/pandas-basics-on-a-real-dataset-a-hands-on-walkthrough-with-palmer-penguins?utm_source=hashnode&utm_medium=feed) Load, inspect, clean, filter, group and pivot real data with pandas. Every snippet was run and the outputs are real. 7 min read · [realdev9868.hashnode.dev](https://realdev9868.hashnode.dev/pandas-basics-on-a-real-dataset-a-hands-on-walkthrough-with-palmer-penguins?utm_source=hashnode&utm_medium=feed) [Oct 19](https://hashnode.com/posts/pandas-basics-on-a-real-dataset-a-hands-on-walkthrough-with-palmer-penguins/6ad58cb707bff221c144f7f0) ### [Belady's Anomaly: FIFO vs LRU vs Optimal, Checked in Python](https://realdev9868.hashnode.dev/belady-s-anomaly-fifo-vs-lru-vs-optimal-checked-in-python?utm_source=hashnode&utm_medium=feed) A GATE CS page-replacement walkthrough on one reference string, plus a script that shows how rare Belady's anomaly really is. 6 min read · [realdev9868.hashnode.dev](https://realdev9868.hashnode.dev/belady-s-anomaly-fifo-vs-lru-vs-optimal-checked-in-python?utm_source=hashnode&utm_medium=feed) [Oct 17](https://hashnode.com/posts/belady-s-anomaly-fifo-vs-lru-vs-optimal-checked-in-python/6ad388fbfe226b8f9f3ee2ce) ### [A 30-Day DSA Plan for Placements, Built Around Patterns (Not Problem Counts)](https://realdev9868.hashnode.dev/a-30-day-dsa-plan-for-placements-built-around-patterns-not-problem-counts?utm_source=hashnode&utm_medium=feed) A common way to prepare for placement coding rounds is to open a list of hundreds of problems and start at number one. A month later, a new problem still feels like a blank page. A better approach: le 7 min read · [realdev9868.hashnode.dev](https://realdev9868.hashnode.dev/a-30-day-dsa-plan-for-placements-built-around-patterns-not-problem-counts?utm_source=hashnode&utm_medium=feed) [Oct 15](https://hashnode.com/posts/a-30-day-dsa-plan-for-placements-built-around-patterns-not-problem-counts/6ad0fe3fe3021620e79bd193)