I had planned to develop kero further. But at the end of the day, that should be just for practice; look at the existing libraries and APIs such as keras and tensorflow: they are already very extensive and also well maintained. On that note, I should remind myself that one does not try to beat the giants in their game, unless I have something really innovative to offer.
That said, while implementing kero, I had had fun reading up the theories down to the fundamental of basic implementation of a neural network. For now, I think exploring tutorials with keras is a good idea as well!
To start this off, here is the first tutorial. Enjoy!
(20190104) second tutorial on MNIST.