public function define(
		$app_name,
		$ext_name,
		callable $app_func = null,
		callable $ext_func = null,
		$app_args = [],
		$ext_args = []
	) {
		$this->definitions[self::EXT][$app_name] = [
			self::DEFINITION_KEY  => $ext_name,
			self::DEFINITION_MAP  => $app_name,
			self::DEFINITION_FUNC => $ext_func,
			self::DEFINITION_ARGS => $ext_args
		];
		$this->definitions[self::APP][$ext_name] = [
			self::DEFINITION_KEY  => $app_name,
			self::DEFINITION_MAP  => $ext_name,
			self::DEFINITION_FUNC => $app_func,
			self::DEFINITION_ARGS => $app_args,
		];
	}