Code example for http://roytomeij.com/2013/should-you-use-a-sass-mixin-or-extend.html

poor_mixin_usage.scss

@mixin hide-text {
  text-indent: -9999px;
  overflow: hidden;
}

.foo {
  @include hide-text;
}

.bar {
  @include hide-text;
}

.baz {
  @include hide-text;
}