This helper function would compare the indexes (possibly on specific collections only) and appropriate members (defaulting to all shards and/or replicas) and output a report detailing any inconsistency (host with indexes missing – from primary – or extras on non-primary).

The implementation should produce machine readable and useable versions as well as a textual report.

Motivation:
The idea is to identify any members of a sharded cluster, or members of a replica set that have a different set of indexes (either missing, or additional) relative to other members - essentially an index "diff".

While this is quite simple to accomplish with a manual inspection when there only a few indexes present, it is quite difficult/laborious when dealing with hundreds of indexes on (potentially) dozens of hosts.