code: func extractWhitespaceTag(message ValidMessage) (plain MessagePlaintext, versions int) {
  	wsPos := bytes.Index(message, whitespaceTagHeader)
  	currentData := message[wsPos+len(whitespaceTagHeader):]
  
  	for {
  		aw, r, has := nextAllWhite(currentData)
  		if !has {
  			break
  		}
  		currentData = r
  		if bytes.Equal(aw, otrV3{}.whitespaceTag()) {
  			versions |= (1 << 3)
  		} else if bytes.Equal(aw, otrV2{}.whitespaceTag()) {
  			versions |= (1 << 2)
  		}
  	}
  
  	plain = makeCopy(append(message[:wsPos], currentData...))
  	return
  }
docs: // By the spec "this tag may occur anywhere in the message"