def add_handler(iface_name, handler)
      iface = @contract.interface(iface_name)
      if !iface
        raise "No interface found with name: #{iface_name}"
      end
      @handlers[iface_name] = handler
    end
def add_handler(iface_name, handler)
      iface = @contract.interface(iface_name)
      if !iface
        raise "No interface found with name: #{iface_name}"
      end
      @handlers[iface_name] = handler
    end
Create a server with the given Barrister::Contract instance
 Register a handler class with the given interface name

 The `handler` is any Ruby class that contains methods for each
 function on the given IDL interface name.

 These methods will be called when a request is handled by the Server.