Generated by SassMeister.com.

input.scss

@mixin flex($justify-content:false, $align-items:false){
    display:flex;
    @if $justify-content{
        justify-content:$justify-content;
    }
    @if $align-items{
        align-items:$align-items;
    }
}

.demo-1 {
    @include flex;
}

.demo-2 {
    @include flex(center);
}

.demo-3 {
    @include flex(false,center);
}

.demo-4 {
    @include flex(center,center);
}

output.css

.demo-1 {
  display: flex;
}

.demo-2 {
  display: flex;
  justify-content: center;
}

.demo-3 {
  display: flex;
  align-items: center;
}

.demo-4 {
  display: flex;
  justify-content: center;
  align-items: center;
}

settings.json

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