"weeder" command

[aryairani]

Is your feature request related to a problem? Please describe.

It's easy to accumulate a lot of cruft in your namespace, possibly more than in text languages because

• deletes in your scratch file generally have no effect
• renaming in your scratch file can lead to a duplicate / variant definition instead of replacing the original
• the branch itself is difficult to browse and "see" with CLI

This cruft adds unnecessary burden to any refactor.

Describe the solution you'd like

It would be nice to have tool support for removing unwanted definitions.
For example:

add a command weed (or whatever) that either accepts 1+ terms or (probably better) defaults to a particular term e.g. roots, which could be a Doc but doesn't have to be, and traverses the namespace, compiling a list of definitions that aren't transitive dependencies of roots.

From there you could do a delete 1-28.

Describe alternatives you've considered
Basically doing this manually, which ucm does at least let you do, with the dependents command, but it would be very tedious. It seems like "manual" and "automatic" covers all the possibilities.

Additional context

[aryairani]

A first cut could be a command that just lists everything that doesn't have dependents. The user can tease apart the roots from the non-roots. cc @SystemFw