Safe get-function in Sass 3.3.x and up

safe-get-function.scss

// Simplified version of safe-get-function
// Full code: https://github.com/kaelig/sass-safe-get-function

@function safe-get-function($name) {
  @if function-exists('get-function') {
    @return get-function($name);
  } @else {
    @return $name;
  }
}

@function foo($x) { @return $x; }

h1 {
  content: call(safe-get-function('foo'), 'Works in all versions of Sass!');
}