This function also has a callback; thus, for each iteration, some logic is applied to the data collected.

这个函数也有一个回调；因此，对于每次遍历，都会有一些逻辑应用于收集的数据。

youdao

Note at the end of the loop that I recursively call the same function with an argument that is one greater than the previous, implementing the iteration of the loop.

注意，在循环的结尾处，我用一个比上次大1的参数递归地调用同一个函数，以实现循环的迭代。

youdao

Because the regular keys iteration of FIRSTKEY and NEXTKEY is only over the primary keys, the secondary_keys function is provided for the secondary mapping.

由于FIRSTKEY和NEXTKEY的常规keys迭代只是对主键进行，因此secondary_keys函数是为第二个映射提供的。

youdao