code: func (storage Storage) Type() string {
  	var storageType []string
  
  	// Return only key in this map
  	for k := range storage {
  		switch k {
  		case "maintenance":
  			// allow configuration of maintenance
  		case "cache":
  			// allow configuration of caching
  		case "delete":
  			// allow configuration of delete
  		case "redirect":
  			// allow configuration of redirect
  		default:
  			storageType = append(storageType, k)
  		}
  	}
  	if len(storageType) > 1 {
  		panic("multiple storage drivers specified in configuration or environment: " + strings.Join(storageType, ", "))
  	}
  	if len(storageType) == 1 {
  		return storageType[0]
  	}
  	return ""
  }
docs: // Type returns the storage driver type, such as filesystem or s3