Generated by SassMeister.com.

SassMeister-input.scss

// ----
// libsass (v2.0.0)
// ----

%Placeholder1 {
  color: red;
}

%Placeholder2 {
  background: black;
  font-family: helvetica;
}

.some-class {
  @extend %Placeholder1;
  
  &:hover {
    color: black;
  }
}

.some-other-class {
  @extend %Placeholder2;
}

.some-class-3 {
  @extend %Placeholder1;
  @extend %Placeholder2;
}

@for $i from 1 through 10 {
  .some-#{$i} {
    @extend %Placeholder1;
    
    border: 1px solid red;
  }
}

SassMeister-output.css

.some-class, .some-class-3, .some-1, .some-2, .some-3, .some-4, .some-5, .some-6, .some-7, .some-8, .some-9, .some-10 {
  color: red; }

.some-other-class, .some-class-3 {
  background: black;
  font-family: helvetica; }

.some-class:hover {
  color: black; }

.some-1 {
  border: 1px solid red; }

.some-2 {
  border: 1px solid red; }

.some-3 {
  border: 1px solid red; }

.some-4 {
  border: 1px solid red; }

.some-5 {
  border: 1px solid red; }

.some-6 {
  border: 1px solid red; }

.some-7 {
  border: 1px solid red; }

.some-8 {
  border: 1px solid red; }

.some-9 {
  border: 1px solid red; }

.some-10 {
  border: 1px solid red; }