code: func filterContentType(info FileInfo) (contentType string, contentDisposition string) {
  	filetype := info.MetaData["filetype"]
  
  	if reMimeType.MatchString(filetype) {
  		// If the filetype from metadata is well formed, we forward use this
  		// for the Content-Type header. However, only whitelisted mime types
  		// will be allowed to be shown inline in the browser
  		contentType = filetype
  		if _, isWhitelisted := mimeInlineBrowserWhitelist[filetype]; isWhitelisted {
  			contentDisposition = "inline"
  		} else {
  			contentDisposition = "attachment"
  		}
  	} else {
  		// If the filetype from the metadata is not well formed, we use a
  		// default type and force the browser to download the content.
  		contentType = "application/octet-stream"
  		contentDisposition = "attachment"
  	}
  
  	// Add a filename to Content-Disposition if one is available in the metadata
  	if filename, ok := info.MetaData["filename"]; ok {
  		contentDisposition += ";filename=" + strconv.Quote(filename)
  	}
  
  	return contentType, contentDisposition
  }
docs: // filterContentType returns the values for the Content-Type and
  // Content-Disposition headers for a given upload. These values should be used
  // in responses for GET requests to ensure that only non-malicious file types
  // are shown directly in the browser. It will extract the file name and type
  // from the "fileame" and "filetype".
  // See https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Disposition