[Feature Request] Adding to D lang "set" built-in

[bioinfornatics]

Dear, i hope i will got some answer from druntime/phobos dev .
A set is an array of unique element:
>>> set( 1, 5, 7, 1, 7)
give this array => [1, 5, 7]

Currently in D the hack it is to use an associative array with any
value.
byte[size_t] a = [ 1:0, 5:0, 7:0, 1:0, 7:0 ];

then it is easy to have a set in D just add a syntax or a built-in where
use associative array without using value.

I hope really this little feature and seem really easy to add


thanks a lot for your great works