Type hints and type check

Type hints is a modern Python way to provide type information (see typing mypy). PR https://github.com/tarantool/tarantool-python/pull/264 is the first one to potentially use type hints, but it would be nice to have it anywhere.

Type asserts is a more tricky question. For now there are some minor type checks and asserts in connector. Some may also be implemented in PR #264. But it is a big question if they should be use. It seems that there are both adepts of using (since it is a convenient concept) and forbidding to use (since it contradicts Python duck typing principle) it. For example, see this StackOverflow thread. One way or another, it would be good to at least have a consistency on this question.

Since now package is fully documented, it should be easy to implement type hints and asserts after one decide what approach we should stick to. But choosing the approach is the question.

首先阅读 PR #264 以及现有的 connector 类型检查和 asserts，然后查看 package 文档和链接的 typing 与 mypy 参考资料。这个 issue 首先需要决定是否添加类型提示，以及如何一致地使用运行时类型检查或 asserts；当达成一致的方法应用于整个 package 时，即视为完成。