// Get single value from key in instance map based on $selector::$key
// -------------------------------------------------------------------------------
// @dependence `map-fetch()`
// -------------------------------------------------------------------------------
// @warning : all [Values] @returned are strings and must be converted with `to-number()`
// -------------------------------------------------------------------------------
// @param $key [Breakpoint] : key
// @param $value [Value] : value
// @param $deep [Value] : fetch deep value
// -------------------------------------------------------------------------------
// @return [Value]

@function get-instance-value($key, $value, $deep: NULL) {
	@if $deep == NULL {
		@return map-fetch($flint__instances, family-instance-exists($key) $value);
	} @else {
		@return map-fetch($flint__instances, family-instance-exists($key) $value $deep);
	}
}