code: func volume(b *Builder, args []string, attributes map[string]bool, flagArgs []string, original string) error {
  	if len(args) == 0 {
  		return errAtLeastOneArgument("VOLUME")
  	}
  
  	if b.RunConfig.Volumes == nil {
  		b.RunConfig.Volumes = map[string]struct{}{}
  	}
  	for _, v := range args {
  		v = strings.TrimSpace(v)
  		if v == "" {
  			return fmt.Errorf("Volume specified can not be an empty string")
  		}
  		b.RunConfig.Volumes[v] = struct{}{}
  		b.PendingVolumes.Add(v)
  	}
  	return nil
  }
docs: // VOLUME /foo
  //
  // Expose the volume /foo for use. Will also accept the JSON array form.
  //