SASS Proposition for extending media queries via output buffer style functions

current-media-queries.scss

/*
 I understand this is how it currently works.
 Also there is a little "convenience" way to do it with some control structures and passing an argument to the mixin, 
 but the resulting code is still the same.
*/

@mixin handhelds() {
  @media only screen and (max-width: 479px) { @content; }
}

.bluespace {
  width: 800px;
  height: 400px;
  background-color: blue;
  @include handhelds() {
    width: 600px;
    height: 300px;
  }
}

.greenspace {
  width: 300px;
  height: 150px;
  background-color: green;
  @include handhelds() {
    width: 200px;
    height: 100px;
  }
}

// ^ Generates this ...
.bluespace {
  width: 800px;
  height: 400px;
  background-color: blue;
}

@media only screen and (max-width: 959px) { // <<== This is all good and well
  .bluespace {
    width: 600px;
    height: 300px;
  }
}

.greenspace {
  width: 300px;
  height: 150px;
  background-color: green;
}

@media only screen and (max-width: 959px) { // <<== But then it gets duplicated & this is no good for the browser :(
  .greenspace {
    width: 200px;
    height: 100px;
  }
}

proposed-buffer-blocks.scss

/*
 Proposition:
 I'm suggesting basically an output buffer that would allow a LOT of flexibility to block styles together.
 I can see this immediately being helpful and effective for media queries. Especially for me personally. 
 Hopefully this makes sense enough to be self explanatory. I'm sure I'm not the first person to think about this
 So maybe someone can answer as to why it might not be implemented yet?
*/

@buffer handhelds {
  @media only screen and (max-width: 959px) {
    @content;
  }  
}

.bluespace {
  width: 800px;
  height: 400px;
  background-color: blue;
  @append handhelds {
    width: 600px;
    height: 300px;
  }
}

.greenspace {
  width: 300px;
  height: 150px;
  @append handhelds {
    width: 200px;
    height: 100px;
  }
}

@flush handhelds;

// Should Generate this ...

.bluespace {
  width: 800px;
  height: 400px;
  background-color: blue;
}

.greenspace {
  width: 300px;
  height: 150px;
}

@media only screen and (max-width: 959px) {
  .bluespace {
    width: 600px;
    height: 300px;
  }
  .greenspace {
    width: 200px;
    height: 100px;
  }
}

Found a related feature request on Sass's issue tracking. Add you're vote, or implement it if you know how.