// 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 [string] : key
// @param $value [number] : value
// @param $deep [number] : fetch deep value
// -------------------------------------------------------------------------------
// @return [string]

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