Sass lets you easily specify multiple selectors at once like this:

.some-block
  &.has-hover,
  &:hover
    outline: 1px solid red

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This will add a red outline on either real hover or when the has-hover class is present. However, adding a comment will void the definition of that line:

.some-block
  &.has-hover, // From hoverable.js <-- DON'T
  &:hover
    outline: 1px solid red

... will simply drop the &.has-hover part in ruby-sass Show archive.org snapshot (deprecated). sassc Show archive.org snapshot and Node Sass Show archive.org snapshot (Dart Sass transpiled to JS) are not affected by this problem.