- [x] [ap](https://ramda.cn/docs/#ap) - [x] [chain](https://ramda.cn/docs/#chain) - [x] [fromPairs](https://ramda.cn/docs/#fromPairs) - [x] [is](https://ramda.cn/docs/#is) - [x] [length](https://ramda.cn/docs/#length) - [x] [mathMod](https://ramda.cn/docs/#mathMod) - [x] [of](https://ramda.cn/docs/#of) - [x] [unnest](https://ramda.cn/docs/#unnest) - [x] [zipObj](https://ramda.cn/docs/#zipObj) - [x] check some todos
