<===> input.scss
@mixin keyframes($animation-name) {
  @keyframes $animation-name {
    @content;
  }
}

@include keyframes(bounce) {
  0%, 20%, 50%, 80%, 100% {transform: translateY(0);}
  40% {transform: translateY(-30px);}
  60% {transform: translateY(-15px);}
}
<===> output.css
@keyframes $animation-name {
  0%, 20%, 50%, 80%, 100% {
    transform: translateY(0);
  }
  40% {
    transform: translateY(-30px);
  }
  60% {
    transform: translateY(-15px);
  }
}