code: function hasProject(name, callback) {
      const config = require(path.resolve(process.cwd(), 'nuts.config.json'));
      fs.exists(`${config.sourceDir}/${name}`, (exists)=> {
          if (exists) {
              callback();
          } else {
              console.log('项目不存在');
          }
      });
  }
docs: 判断项目是否正确
  @param name
  @param callback