bsf_core_url( string $append = '' )

	function bsf_core_url( $append = '' ) {
		$path       = wp_normalize_path( BSF_UPDATER_PATH );
		$theme_dir  = wp_normalize_path( get_template_directory() );
		$plugin_dir = wp_normalize_path( WP_PLUGIN_DIR );

		if ( strpos( $path, $theme_dir ) !== false ) {
			return rtrim( get_template_directory_uri() . '/admin/bsf-core/', '/' ) . $append;
		} elseif ( strpos( $path, $plugin_dir ) !== false ) {
			return rtrim( plugin_dir_url( BSF_UPDATER_FILE ), '/' ) . $append;
		} elseif ( strpos( $path, dirname( plugin_basename( BSF_UPDATER_FILE ) ) ) !== false ) {
			return rtrim( plugin_dir_url( BSF_UPDATER_FILE ), '/' ) . $append;
		}

		return false;
	}