title: concurrent map iteration and map write error in Golang 1.8
body: <p>So I have this func.. </p>
  
  <pre><code>func Set(firstSet map[string][]App, store map[string]*Parsed) map[string][string]struct{} {
      s := make(map[string]map[string]struct{})
      for dmn, parsed := range store {
          for cId, apps := range firstSet {
              if _, ok := s[dmn]; !ok {
                  s[dmn] = make(map[string]struct{})
              }
              s[dmn][cId] = struct{}{}
          }
      }
  
      return s
  }
  </code></pre>
  
  <p>Line 3 of that func (for dmn, parsed := range store) is giving me the error concurrent map iteration and map write error in Golang 1.8. any idea?</p>