What this is

No new concepts in this lesson. This is a checkpoint: a small, real script built entirely out of ideas from Lessons 1 through 8, combined into one thing. If you can read lesson.py and understand why every piece is there, you've mastered the Beginner tier. If any piece feels unfamiliar, that's a sign to revisit the lesson it came from before continuing to Intermediate.

What it does

Builds one knowledge graph from every fixture note in lessons/graph_rag/fixtures/notes/ (six short Markdown files about a household's greenhouse, garage workshop, shared electronics bench, and more), then answers three questions, each requiring a different number of hops across the graph, printing the whole run so you can see traversal reach further for a harder question and stop sooner for an easier one.

Where each piece came from

def build_graph(notes_dir: Path) -> Graph:
    graph: Graph = {}
    for path in sorted(notes_dir.glob("*.md")):
        for subject, relation, obj in extract_relationships(path.read_text()):
            add_edge(graph, subject, relation, obj)
    return graph

Lesson 8, unchanged: extract from every fixture, merge every triple into one shared graph.

facts = gather_facts(graph, start_entity, max_hops)

Lesson 7's traversal, unchanged: walk outward from a starting entity, collecting every edge encountered within max_hops hops.

answer = generate_answer(query, facts)

Lesson 7's generation, unchanged: turn gathered facts into a grounded answer, honest about what the facts don't establish.

def ask(query: str, graph: Graph, start_entity: str, max_hops: int = 2) -> str:
    facts = gather_facts(graph, start_entity, max_hops)
    return generate_answer(query, facts)

The whole pipeline as one function call, this course's first ask(), the same shape naive_rag Lesson 8 introduced for its own pipeline.

Try this yourself

Without looking anything up:

  • Change max_hops from 2 to 1 for the greenhouse-sensor question, does it still get answered, or does traversal stop one hop short of Mia and the multimeter?
  • Pick a different starting entity for the same question ("Dev" instead of "humidity sensor"), does the answer come out the same?
  • Add a fourth question of your own that needs the book club and the electronics bench connected (both mention the soldering station), and pick a starting entity for it yourself.

If you can make these changes confidently, you're ready for the Intermediate tier, starting at Lesson 10.