def handle_prefix(client, data)
      prefix, uri = data

      topic = @engine.find_or_create_topic(uri)
      client.add_prefix(prefix, topic)

      trigger(:prefix, client, prefix, uri)
    end
def handle_prefix(client, data)
      prefix, uri = data

      topic = @engine.find_or_create_topic(uri)
      client.add_prefix(prefix, topic)

      trigger(:prefix, client, prefix, uri)
    end
Handle a prefix message from a client
 PREFIX data structure [PREFIX, URI]