number of arguments

[e5b0953](https://github.com/kangwonlee/gemini-python-tutor/commit/e5b0953e73b85c88b50f264708439eaced7cb695)
* README.md may require one argument for a function under test
* `pytest` would call the function under test with one argument
* LLM may find it is a problem of the `pytest`

Start by reviewing README.md and commit e5b0953, then trace how pytest invokes the function under test when an argument is required. Compare that behavior with the tutor's handling of the assignment and determine the expected result for one-argument functions. Done means the behavior or guidance is consistent and verified with the relevant pytest case.

Scritto dal modello di indicizzazione a partire dal testo della issue.