Variable arguments in a Sass mixin or function

gistfile1.scss

@mixin corners($corner...) {
  border-radius: $corner;
}

.round-corners {@include corners(1rem 1em 1vw 1vmin);}

/// compiles to:
///
/// .round-corners {border-radius: 1rem 1em 1vw 1vmin;}
/// official docs: http://sass-lang.com/documentation/file.SASS_REFERENCE.html#variable_arguments
/// example: http://codepen.io/ryanallen/pen/azWWOG