Interesting that we were already using `be_between` even without the better matcher :).

That said, this spec is meant to test the dynamic predicate matchers (e.g. `be_xyz` => `xyz?`) but now it's not calling the predicate anymore so it would be good to update the description of this example to indicate it's for `be_between` and then make a different example for predicate matchers.  I was thinking we could use `Fixnum#odd?` or `Fixnum#even?` (`be_odd` and `be_even`, respectively) but part of the point here is to verify that the arguments are formatted well in the description.  I can't think of another built-in ruby predicate that takes multiple arguments.  Can you?