<% example do %>
  $sizes: 40px, 50px, 80px;

  @each $size in $sizes {
    .icon-#{$size} {
      font-size: $size;
      height: $size;
      width: $size;
    }
  }
  ===
  $sizes: 40px, 50px, 80px

  @each $size in $sizes
    .icon-#{$size}
      font-size: $size
      height: $size
      width: $size
<% end %>