Strip() and Assert() functions; original version

SassMeister-input.scss

// ---
// Breakpoint (v2.0.5)
// Sass (v3.2.8)
// ---


// fiddling with auto conversion between rem and px

$base-font-size: 16;

// remove and set units
@function remove-unit($n) { @return $n / ($n * 0 + 1); }
@function set-unit($n, $u) { @return remove-unit($n) * 1#{$u}; }

// aliases of above to "strip" and "assert"
@function strip($n) { @return remove-unit($n); }
@function assert($n, $u) { @return set-unit($n, $u); }

// px to rem and vice versa
@function px2rem($p) { @return assert($p / $base-font-size, rem); }
@function rem2px($r) { @return assert($r * $base-font-size, px); }

// tests
$mobile: px2rem(480); //480px
.test {
    @include breakpoint($mobile) {
        width: px2rem(100px);
    }
}

SassMeister-output.css

@media (min-width: 30rem) {
  .test {
    width: 6.25rem;
  }
}