Polymorphic ranges?

[Andrej Mitrovic]

I'm not sure how to use those wrappers though. Maybe I'm just doing it wrong:

http://codepad.org/eHIdhasc

But it seems these wrappers have some problems, the docs say about the
interfaces:

Limitations:
These interfaces are not capable of forwarding ref access to elements.
Infiniteness of the wrapped range is not propagated.
Length is not propagated in the case of non-random access ranges.