当我们从github上下载了blockly之后，打卡demos下的index.html时，选择blockly-developer-tools时会弹出一个对话框（大体内容是closure dependency not found），此时我们需要下载这个文件，解压并且命名为closure-library，放在和blockly同目录下，然后重新选择就好了。
The blockly-android project is no longer actively developed by the Google Blockly team. We will continue to review and accept pull requests. If you are looking to create a new Blockly-based app, we recommend using the web version in a WebView. We ha
