title: Get an arbitrary key/item from a map
body: <p>I am new to Go and now I want to get an arbitrary item from a map; what's the idiomatic way to do that? I can only think of something like this:</p>
  
  <pre><code>func get_some_key(m map[int]int) int {
      for k := range m {
          return k
      }
      return 0
  }
  </code></pre>
  
  <p>The reason I want that is I am using a map to maintain a set of jobs, and with a map I can get a pending job or remove a finished job in O(1). I guess this should be a common requirement but it's not obvious how to do it in Go. </p>