how do I tell if something is lvalue?

[Meta via Digitalmars-d-learn]

On Sunday, 31 January 2016 at 22:11:45 UTC, Steven Schveighoffer 
wrote:
> On 1/31/16 4:48 PM, Meta wrote:
>
>>
>> This seems to do the trick, although I haven't extensively 
>> tested it.
>> There's probably a simpler way but this is the first thing I 
>> could come
>> up with that works.
>>
>>
>
> Thanks! I was surprised this is not straightforward.
>
> -Steve

It seems to me like it would be a useful addition to __traits.