Defer in Go example

deferInGo.go

// Taken from https://golang.org/doc/effective_go.html#defer
func Contents(filename string) (string, error) {
  f, err := os.Open(filename)
  if err != nil {
      return "", err
  }
  
  defer f.Close()  // f.Close will run when we're finished.
  
  var result []byte
  return string(result), nil // f closed here
}