Make a symlink in install folder to a local NApp.

        Raises:
            FileNotFoundError: If NApp is not found.

def install_local(self):
        """Make a symlink in install folder to a local NApp.

        Raises:
            FileNotFoundError: If NApp is not found.

        """
        folder = self._get_local_folder()
        installed = self.installed_dir()
        self._check_module(installed.parent)
        installed.symlink_to(folder.resolve())