Module
Start the graph, open a nested callback with Lambda, and return from the main path or a body.
Module blocks sit in the builder palette under Basic → Module. Shared graph rules are on Workflows.
Every graph already has Start. You do not drag it from the palette, and you cannot delete it. Lambda opens a callback (nested) scope from a parent Callback outlet. Return (canvas label End) finishes a path — the whole workflow on the main path, or this body inside a callback.
A loop (or similar) Callback outlet does not stay on the main path. Put Lambda on that outlet, build the body, and return from the body — that return is for the callback, not for the whole workflow.