I think you're right that we do want to be able to support such distributions.  I've just noticed below that the `xmin`, `xmax` finder might grind to a halt in the central valleys of multi-modal distributions.  However, I think that's a very tough nut to crack in any general way (ask people into sampling...) so a caveat in the documentation about it being recommended to specify `xmin` and `xmax` when supplying a function if your input function is multi-modal.