code: function handleFieldsTree (api) {
              // 排除名单
              var ex = ['function', 'desc', 'param', 'example'];
              if ( api && typeof api === 'object' ) {
                  for ( var i in api ) {
                      if ( ex.indexOf(i) === -1 ) {
                      // grunt.log.writeln(i)
                          var field = api[i];
                          // console.log(field)
                          var tmp = [];
                          // grunt.log.writeflags(field)
                          if ( field && field.forEach ) {
                              field.forEach(function (item, k) {
                                  if ( item.belong ) {
                                      tmp.push(k);
                                      handleFieldBelong(i, item.belong.split('.'), api.param, item)
                                  }
                              });
                              if ( tmp.length ) {
                                  for ( var m = tmp.length; m-- ; m >= 0 ) {
                                      // console.log(tmp[m])
                                      field.splice(tmp[m],1)
                                  }
                              }
                              // clear
                              if ( !field.length ) delete api[i];
  
                          }
                      }
                  }
              }
          }
docs: 其他字段层级化 `note` `support` `importent` etc