code: func allPackagesInFS(pattern string) []string {
  	pkgs := matchPackagesInFS(pattern)
  	if len(pkgs) == 0 {
  		fmt.Fprintf(os.Stderr, "warning: %q matched no packages\n", pattern)
  	}
  	return pkgs
  }
docs: // allPackagesInFS is like allPackages but is passed a pattern
  // beginning ./ or ../, meaning it should scan the tree rooted
  // at the given directory.  There are ... in the pattern too.