chriseppstein/sass — comment on commit 52c9084c1e1258473d00274fbf210d6c44ae14ad
File: doc-src/SASS_REFERENCE.md line 1475
By akai:

Or, this is a mixin declaration:

``` css
.grid-column {
float: left;
margin-right: 10px;
}
```

extend with a prefix `!`:

``` scss
@for $g from 1 through 4 {
.span-#{$g} {
!@extend .grid-column;
width: 40px * $g + 10px * ($g - 1);
}
}
```