Get variable name from variable value in SASS/SCSS - css

Question

I'd like to access variable within an #each loop using defined value like in the following example:
$car:true;
$people:false;
$job:false;
#mixin options($someval){
#each $prefix in car,people,job{
#if $#{$prefix} == true{
//some CSS...
}
}
}
Variable would be a sort of "semaphores" that define whether print or not Css rules.
My big doubt is how can I check over dynamically defined variables name ?
I've tried with $#{$prefix} but it doesn't work.
EDIT ---------------------------
I'd like to obtain this CSS
car-something: 34px;
Where the word "car" is taken from $prefix and in the first round of #each loop $#{$prefix} becomes $car
The problem is on $#{$prefix} ... it doesn't work :P i get an error

Answer 1

This is an old question but since it has no valid answer, here it is
You need to pass a map to #each
$car:true;
$people:false;
$job:false;
#mixin options($someval){
#each $key, $val in (car: $car, people: $people, job: $job) {
#if $val == true{
#{$key}-something: $someval
}
}
}
test {
#include options(34px)
}

Answer 2

Instead of trying to interpolate a variable name, pass a list to the mixin.
$car: true;
$people: false;
$job: false;
$thing-list: $car, $people, $job;
#mixin thingamajig($thing-list) {
#each $thing in $thing-list {
#if $thing {
// Some CSS
}
}
}