# File lib/stomp/client.rb, line 172
    def subscribe(destination, headers = {})
      raise "No listener given" unless block_given?
      # use subscription id to correlate messages to subscription. As described in
      # the SUBSCRIPTION section of the protocol: http://stomp.github.com/.
      # If no subscription id is provided, generate one.
      headers = headers.merge(:id => build_subscription_id(destination, headers))
      if @listeners[headers[:id]]
        raise "attempting to subscribe to a queue with a previous subscription"
      end
      @listeners[headers[:id]] = lambda {|msg| yield msg}
      @connection.subscribe(destination, headers)
    end