How do I use a mixin param in a each loop? - sass

Question

I'm trying to create a BEM spacing helper mixin that contains the name of the screen in the class name. An example output: .marSm0 .marSm0__t .marSm0__b .marSm0__x
$emMd0: 1em !default;
$emMd1: 1.5em !default;
$emMd2: 2em !default;
$emMd3: 4em !default;
$emMdSpacing: ($emNone, $emMd0, $emMd1, $emMd2, $emMd2 );
#mixin spacingHelper($screenSize, $spacingValues){
#each $space in $spaceValues {
.mar#{screenSize}#{$space} {
margin: #{$space}rem;
}
.mar#{screenSize}#{$space}__x {
margin-left: #{$space}rem;
margin-right: #{$space}rem;
}
.mar#{screenSize}#{$space}__y {
margin-top: #{$space}rem;
margin-bottom: #{$space}rem;
}
.mar#{screenSize}#{$space}__l {
margin-left: #{$space}rem;
}
.mar#{screenSize}#{$space}__r {
margin-right: #{$space}rem;
}
.mar#{screenSize}#{$space}__b {
margin-bottom: #{$space}rem;
}
.mar-#{screenSize}#{$space}__t {
margin-top: #{$space}rem;
}
.pad#{screenSize}#{$space} {
padding: #{$space}rem;
}
.pad#{screenSize}#{$space}__x {
padding-left: #{$space}rem;
padding-right: #{$space}rem;
}
.pad#{screenSize}#{$space}__y {
padding-top: #{$space}rem;
padding-bottom: #{$space}rem;
}
.pad#{screenSize}#{$space}__l {
padding-left: #{$space}rem;
}
.pad#{screenSize}#{$space}__r {
padding-right: #{$space}rem;
}
.pad#{screenSize}#{$space}__b {
padding-bottom: #{$space}rem;
}
.pad#{screenSize}#{$space}__t {
padding-top: #{$space}rem;
}
}
}
The problem I'm having is that the $screenSize mixin argument isn't working in the each loop. How do I fix this? I'm sure if the each loop is having a scope issue. Code
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