flow_view_deps() with :

• dashed lines where function wasn't called
• count of calls
  • on the lines for package/promoted functions
  • After the function name, e.g. "vctrs::vec_size x3" for external/demoted functions
• optionally just hide unused deps (promoted and demoted)
• we might give an index to blocks ordered by first access to the function, so we can have a rough idea of call order at a glance, maybe prototype without it

How it might work :

• We can get all relevant functions through a call to flow::flow_view_deps(fun)$data, though we'll need to enrich the data.
• Then we can trace these functions so they populate a global variable in the package, recording calls and counts relative to calls
• run the call, with same returning options as flow_run()

If trace is too slow because of overheads (and the need to use match.call() rather than sys.call() we can edit the body "manually".

cc @krlmlr