debug = x overrides command line

[Gary Willoughby via Digitalmars-d]

On Tuesday, 21 October 2014 at 19:58:40 UTC, anonymous wrote:
> On Tuesday, 21 October 2014 at 19:51:34 UTC, Gary Willoughby
> wrote:
>> Ah, where's the documentation for this?
>
> http://dlang.org/function.html#pure-functions
>
>> As a concession to practicality, a pure function can:
> [...]
>> perform impure operations in statements that are in a 
>> ConditionalStatement controlled by a DebugCondition.

Right, that's all well and good but where does it say that you 
can assign a value to the debug keyword (in code) and it executes 
as if you had specified debug on the command line?