Generated by SassMeister.com.

input.scss

// lists
$directions: (
  "t": top,
  "r": right,
  "b": bottom,
  "l": left
);

// borders
.ba {
  border: 1px solid red !important;
}
.bn {
  border: 0 none !important;
}

@each $name, $dir in $directions {
  .b#{$name} {
    border-#{$dir}: 1px solid red !important;
  }
}

output.css

.ba {
  border: 1px solid red !important;
}

.bn {
  border: 0 none !important;
}

.bt {
  border-top: 1px solid red !important;
}

.br {
  border-right: 1px solid red !important;
}

.bb {
  border-bottom: 1px solid red !important;
}

.bl {
  border-left: 1px solid red !important;
}

settings.json

{
  "sass": {
    "compiler": "dart-sass/1.26.11",
    "extensions": {},
    "syntax": "SCSS",
    "outputStyle": "expanded"
  },
  "autoprefixer": false
}