Generated by SassMeister.com.

SassMeister-input.scss

// ----
// libsass (v3.2.5)
// ----

$value1: null;
$color1: red;

@function fallback($value, $default) {
  @if $value != null {
    @return $value;
  }
  @else {
    @return $default;
  }
}
div {
    color: fallback($value1, $color1);
}  

SassMeister-output.css

div {
  color: red;
}