@function __exec($function, $args...) {
  @if function-exists($function) {
    @return call(get_function($function), $args...);
  }
  
  @return __call($function, null, $args...);
}

/// Dynamically calls a standard Sass function, similar to 
/// `call($function, $args...)`, with the ability to call scoped 
/// functions, such as those returned from Sassdash functions like
/// `_bind()`, `_callback()`, etc., that otherwise can't be called via `call()`.
/// 
/// @access public
/// @group Function
/// @param {Function} $function - The function/Sassdash callback to call.
/// @param {Any...} $args... - The arguments to apply to the function.
/// @returns {*} Returns the result of calling `$function` with the given `$args...`.
/// @example scss
/// $is-primary: _callback(('color': $color-primary));
/// 
/// $theme: (
///     'name': 'sassdash-theme',
///     'color': $color-primary
/// );
/// 
/// $foo: _exec($is-primary, $theme);
/// // => true
@function _exec($args...) {
    @return call(get-function('__exec'), $args...);
}