Looking at the code (src/microsearch/engine.py), we have:

    class SearchEngine:
        def __init__(self, k1: float = 1.5, b: float = 0.75):
            self._index: dict[str, dict[str, int]] = defaultdict(lambda: defaultdict(int))
            self._documents: dict[str, str] = {}
            self.k1 = k1
            self.b = b

I've no idea what `k1` or `b` are. Nor is there a single comment in the entire file. Are comments considered unfashionable these days?

Looking at `_documents`, I'm guessing the keys are URLs and the values contents of those URLs, but i might be wrong.

The whole thing looks like it would've been a useful resource for people to learn how to build search engines with, that people could build on, had the writer been bothered to document it. But as it is I'm disappointed with the poor code.