@mixin flat-1 {
  display: block;
  clear: both;
}

@mixin flat-2 {
  display: block;
  clear: both;
}

@mixin scoped {
  &__scoped {
    font-weight: bold;
  }
}

@mixin mixed-1 {
  display: block;
  clear: both;

  & {
    font-weight: bold;
  }

  .nested {
    font-weight: normal;
  }

  color: red;
  font-weight: bold;
}

@mixin mixed-2 {
  display: block;
  clear: both;

  & {
    font-weight: bold;
  }

  .nested {
    font-weight: normal;
  }

  color: red;
  font-weight: bold;
}

.a {
  color: red;

  &--serious {
    font-weight: bold;
  }

  font-weight: normal;
  text-decoration: underline;
}

.b {
  @include flat-1;
  color: red;
  @include mixed-1;
  font-size: 16px;
  @include scoped;
}

.c {
  @include scoped;
  color: red;
  @include flat-2;
  @include mixed-2;
}

// This is bad because the mixin is known to contain nested rules,
// therefore the rule that comes after it should be wrapped.
.d {
  @include external-mixin-known-to-contain-nested-rules;

  color: red;
}