@function dp-size($size: 'normal') {
  @if map-has-key($dp-size-units, $size) {
    $value: map-get($dp-size-units, $size);
    
    @if unit($value) != "" {
      @return $value;
    }

    @return $value * $dp-base-size;
  }

  @error "#{$size} is not a valid unit factor";
}