How can I sort a Map[string]int by its values?

Given this code block

map[string]int {"hello":10, "foo":20, "bar":20}

I would like to print out

foo, 20
bar, 20
hello, 10

In the order of highest to lowest

Found the answer on Golang-nuts by Andrew Gerrand

You can implement the sort interface by writing the len/less/swap functions

func rankByWordCount(wordFrequencies map[string]int) PairList{
  pl := make(PairList, len(wordFrequencies))
  i := 0
  for k, v := range wordFrequencies {
    pl[i] = Pair{k, v}
    i++
  }
  sort.Sort(sort.Reverse(pl))
  return pl
}

type Pair struct {
  Key string
  Value int
}

type PairList []Pair

func (p PairList) Len() int { return len(p) }
func (p PairList) Less(i, j int) bool { return p[i].Value < p[j].Value }
func (p PairList) Swap(i, j int){ p[i], p[j] = p[j], p[i] }

For the original post, please find it here https://groups.google.com/forum/#!topic/golang-nuts/FT7cjmcL7gw