My First Open Source Contribution: Lessons From the Blockchain Module

For a long time, I wanted to contribute to open source but always thought: “I know nothing, I’ll just break things.” Today, I finally did it — and I want to record every step, including the mistakes I made, how I fixed them, and what I learned.

Step 1: Picking a Project

I forked the TheAlgorithms/Python repository. It’s a large project, but it has clear contribution rules:

Return results (no print statements)
Add type hints
Write doctests or tests
Document time/space complexity

That gave me a roadmap. I decided to focus on the blockchain/diophantine_equation.py file and add a helper function.

Step 2: Writing the Function

I implemented all_diophantine_solutions(a, b, c, n=2). This function returns up to n integer solutions to a linear Diophantine equation.

My first draft looked fine, but then the real learning began…

Step 3: My Mistakes (and Fixes)

❌ Mistake 1 — Wrong Import Placement

I added:

from __future__ import annotations

in the middle of the file. Result:

SyntaxError: from __future__ imports must occur at the beginning of the file

✅ Fix: Either move it to the very top or remove it. I removed it, since Python 3.9+ already supports modern type hints.

❌ Mistake 2 — Function Below `main`

I put my function after:

if __name__ == "__main__":
    from doctest import testmod
    ...

That broke the style rules. ✅ Fix: Always place new functions above the __main__ block.

❌ Mistake 3 — Line Too Long

One docstring line exceeded 88 characters. ✅ Fix: Wrap long lines so the linter (ruff) is happy.

❌ Mistake 4 — f-String in Exception

I wrote:

raise ValueError(f"No integer solutions exist for a={a}, b={b}, c={c}")

Lint error:

EM102 Exception must not use an f-string literal, assign to variable first

✅ Fix:

msg = f"No integer solutions exist for a={a}, b={b}, c={c}"
raise ValueError(msg)

❌ Mistake 5 — Running Doctests

When I tried:

python3 -m doctest -v blockchain/diophantine_equation.py

I got:

ModuleNotFoundError: No module named 'maths'

✅ Fix: Run doctests from the project root so relative imports resolve correctly:

cd ~/contri_pt/Python
python3 -m doctest -v blockchain/diophantine_equation.py

Step 4: Passing the Checks

After fixing everything, I ran:

python3 -m doctest -v blockchain/diophantine_equation.py
pre-commit run --all-files --show-diff-on-failure
ruff check

And finally — all tests passed ✅.

Step 5: Committing and Pushing

From the project root:

git add blockchain/diophantine_equation.py
git commit -m "feat(blockchain): add all_diophantine_solutions with type hints & doctests"
git push -u origin feat/blockchain-diophantine-return-list

Then I opened a pull request to the upstream repo.

Lessons Learned

Start small. One helper function is enough for a first contribution.
Linters are your teachers. Every error message told me exactly what to fix.
Read the rules carefully. TheAlgorithms project enforces strict style, and I had to adapt.
Don’t panic at errors. Most of my time was spent fixing mistakes — and that’s normal.

Final Thoughts

My first open-source contribution wasn’t smooth — I made syntax mistakes, style mistakes, and even ran commands in the wrong directory. But that’s the point: every error was part of the learning.

Now, I have my first PR ready for review. It feels amazing. 🚀

If you’re a beginner: fork a project, pick a small function, add tests, and let the tools guide you. Open source is not about being perfect — it’s about learning in public.