My idea was that these methods are like constructors, and Query is like a module. But I no longer like this because other methods also return objects and there is no clear distinction. So now I think only modules should start with upper case. So now, to use these:
local abc = Io.uri "file:abc"
local Db = Lucene.index(some_dir)
local Query = Db.query
If you want to think of an object as a module, then you can capitalize the local var, but the methods and members remain lower case. Does this make sense?