scope(map)

Given a map node in a map-based tree, this returns a new map representing the tree scope for that node. This effectively merges that map node with all of its ancestors into a single map.

For example, take this file system hierarchy:

package.json
ReadMe.md
src/
  assets/
    image1.jpg
  greet.js
  site.ori

Given a reference to the src folder, calling Tree.scope(src) creates a map that has these keys in order:

- assets/
- greet.js
- site.ori
- package.json
- ReadMe.md
- src/

This scope includes the keys in src and the keys of its ancestors (here, just the parent folder). The image1.jpg file is not in the scope, because it is not directly contained by src or any of its ancestors.