code: func (plugin *flexVolumePlugin) isUnsupported(command string) bool {
  	plugin.Lock()
  	defer plugin.Unlock()
  	for _, unsupportedCommand := range plugin.unsupportedCommands {
  		if command == unsupportedCommand {
  			return true
  		}
  	}
  	return false
  }
docs: // Returns true iff the given command is known to be unsupported.