A request for polling a socket and the poll result.
To create the request, see Socket::new_pollfd.
To get the result, see PollFd::can_read and PollFd::can_write.
A type-safe socket wrapper around nanomsg’s own socket implementation. This
provides a safe interface for dealing with initializing the sockets, sending
and receiving messages.
Type-safe protocols that Nanomsg uses. Each socket
is bound to a single protocol that has specific behaviour
(such as only being able to receive messages and not send them).