compile-time test against dmd/phobos version number

[Jon Degenhardt via Digitalmars-d-learn]

Is there a way to make a compile time check against the 
dmd/phobos version number? Functionally, what I'd like to achieve 
would be equivalent to:

     version(dmdVersion >= 2.070.1)
     {
         ....
     }
     else
     {
         ...
     }

I think I've seen something like this, probably using 'static 
if', but can't find it now. What I'm really trying to do is test 
for existence of a specific enhancement in phobos, if it's 
present, use it, otherwise don't. Testing for a particular phobos 
release number seems the obvious thing to do.

--Jon