cfunction
(net/listen host port &opt type)
Creates a server. Returns a new stream that is neither readable nor
writeable. Use net/accept or net/accept-loop be to handle connections
and start the server. The type parameter specifies the type of
network connection, either a :stream (usually tcp), or :datagram
(usually udp). If not specified, the default is :stream. The host and
port arguments are the same as in net/address.