NBD — Network Block Device — is a protocol for accessing Block Devices
(hard disks and disk-like things) over a Network.

This is the NBD client library in userspace, a simple library for
writing NBD clients.

The key features are:

* Synchronous and asynchronous APIs, both for ease of use and for
writing non-blocking, multithreaded clients.

* High performance.

* Minimal dependencies for the basic library.

* Well-documented, stable API.

* Bindings in several programming languages.