lab1.scss

@mixin abs-pos($top:auto,$left:auto,$bottom:auto,$right:auto) {
  position:absolute;
  top: #{$top}px;
  bottom:$bottom;
  left:$left;
  right:$right;
}

.test {
  @include abs-pos($top:10,$left:10);
}

lab2.scss

@mixin link-color($normal,$hover) {
  a {
    color:$normal;
  }
  
  a:hover,a:focus {
    color:$hover;
  }
}

@mixin ellipsis {
  overflow:hidden;
  text-overflow:ellipsis;
  white-space: nowrap;
}

.testlink {
  @include link-color(#371,#0F0);
}

.test {
  @include ellipsis;
}