Format Sass nested mixins

[matype]

input:

@mixin test() {
  $values: blue red;
@each $val   in $values {
  color  : $val;
  @for $i   from  2   through    10 {
   background: $i;
  }
}
@for $i from 2 through 10 {
  color: $i;
}
}

we will get:

@mixin test() {
  $values: blue red;

  @each $val in $values {
    color: $val;

    @for $i from 2 through 10 {
      background: $i;
    }
  }

  @for $i from 2 through 10 {
    color: $i;
  }
}

#49