# File lib/ffi-rzmq/device.rb, line 17
    def initialize(frontend, backend, capture=nil)
      [["frontend", frontend], ["backend", backend]].each do |name, socket|
        unless socket.is_a?(ZMQ::Socket)
          raise ArgumentError, "Expected a ZMQ::Socket, not a #{socket.class} as the #{name}"
        end
      end

      LibZMQ.zmq_proxy(frontend.socket, backend.socket, capture ? capture.socket : nil)
    end