[Proposal] New function based on EachKey

[marperia]

EachKey gets an array of strings as a parameter, but it would be quite better for me to iterate over map data structure. Could you please make a function with paths specified this like?

myGreatPaths := map[string][]string{
	"event": []string{"event"},
	"user_id": []string{"arg", "uid"},
	...
}