Dmitry did the impossible - wrote a back from 0 in a short time, and the most important thing - wrote an adequately working back.
The professional, responsiblely approaches the task, learns all the necessary nuances, in the process of misunderstanding asks questions and it’s good, as it comes from the first attempt the working product.
I strongly recommend. He added himself to the base of "selected" programmers with whom it's easy to work with.