code: func (ctx *ResourceTransformationCtx) PublishSourceMap(content string) error {
  	target := ctx.OutPath + ".map"
  	f, err := ctx.OpenResourcePublisher(target)
  	if err != nil {
  		return err
  	}
  	defer f.Close()
  	_, err = f.Write([]byte(content))
  	return err
  }
docs: // PublishSourceMap writes the content to the target folder of the main resource
  // with the ".map" extension added.