Part of bzrlib.help View In Hierarchy
It is currently separate to the HelpTopicRegistry because of its ordered nature, but possibly we should instead structure it as a search within the registry and add ordering and searching facilities to the registry. The registry would probably need to be restructured to support that cleanly which is why this has been implemented in parallel even though it does as a result permit searching for help in indices which are not discoverable via 'help topics'.
Each index has a unique prefix string, such as "commands", and contains help topics which can be listed or searched.
|Method||search||Search for topic across the help search path.|
|Method||_check_prefix_uniqueness||Ensure that the index collection is able to differentiate safely.|