// margin and padding
@each $prop-abbr, $prop in (m: margin, p: padding) {
  @each $dir-abbr, $dir in $space-dir {
    @for $i from 1 through 5 {
      .my-#{$prop-abbr}#{$dir-abbr}-#{$i} {
        $hyphen: if($dir, '-', null);
        #{$prop}#{$hyphen}#{$dir}: #{$i/2}em;
      }
    }
  }
}