code: func _MSet(filename string, keys, values []string) error {
  	if len(keys) != len(values) {
  		return fmt.Errorf("number of keys is different to number of values")
  	}
  
  	// Check if the key is already used.
  	conf, err := shconf.ParseFile(filename)
  	if err != nil {
  		if err != os.ErrNotExist {
  			return err
  		}
  		println("ErrNotExist") //TODO: remove
  	}
  
  	var buf bytes.Buffer
  	for i, key := range keys {
  		if _, err = conf.Get(key); err != nil {
  			continue // TODO: log key already set.
  		}
  
  		buf.WriteString(key)
  		buf.Write(conf.Separator())
  		buf.WriteString(values[i])
  		buf.WriteByte('\n')
  	}
  
  	return file.Append(filename, buf.Bytes())
  }
docs: // _MSet sets multiple values named by the keys in the given filename.