File this under "trivial, but annoying", but it should be fixed.

See the attached screen-shot, from http://api.mongodb.org/python/current/api/pymongo/mongo_replica_set_client.html#pymongo.mongo_replica_set_client.MongoReplicaSetClient. It looks like the first optional argument is "hosts_or_un", with some kind of smudge after it.

The problem is that the text "hosts_or_uri" is set in italics, and it runs into the non-italic square bracket, making it unreadable. Whatever markup generator you're using should be smart enough to insert some extra space when you switch from italics to roman.