pop & popFront combined

["Nordlöw" via Digitalmars-d-learn]

On Saturday, 20 September 2014 at 19:23:46 UTC, Jakob Ovrum wrote:
> Sometimes after popping, the previous `front` is no longer 
> valid, such as in the case of a buffer being reused.

Is there a suitable trait we can use to detect this and in turn 
use to disallow stealFront() and stealBack() in these cases?

  We should
> be careful about promoting using a previously read `front` 
> after `popFront` until we figure out what we want to do about 
> these "transient ranges".