anchor.diff:  
   === PONG
   
  -This is a client frame that's used for reply the `PING` frames. Also used for keepalive
  -control.
  +This is a client frame that's used for reply the `PING` frames. Also used for
  +keepalive control.
   
   ----
   PONG
  
positive.code: ----
  MESSAGE
  id: e11a27d3-4b86-4191-a310-12847fa79d48
  topic: user.notifications
  content-type: application/edn
  
  {:foo "bar"}^@
  ----
  
  WARNING: Nothing prevents server send `MESSAGE` frames independently if you have done a
  subscription or not (ex: the server can start sending notifications to the client at
  any time, no subscription action is nedded). The `SUBSCRIBE` frame is a semantic frame
  that allows subscription negotiation if the user needs it.
  
  
  === UNSUBSCRIBE
  
  This is a frame that should be used for cancel a subscription.
  
  [source, text]
  ----
  UNSUBSCRIBE
  id: e11a27d3-4b86-4191-a310-12847fa79d48
  topic: user.notifications
  ----
  
  As consecuence of send this frame, the server should send back to the client the `ACK`
  frame confirming that the server had successfully removed the subscription.
  
  
  === PUBLISH
  
  This is a frame that should be used for publish a message in a specified topic. If a
  client is also subscribed to the topic, it will receive the published message.
  
  [source, text]
  ----
  PUBLISH
  id: e11a27d3-4b86-4191-a310-12847fa79d48
  topic: user.notifications
  content-type: application/edn
  
  {:message "content"}^@
  ----
  
  
  As consecuence of send this frame, the server should send back to the client the `ACK`
  frame confirming that the publish is done successfully.
  
  [source, text]
  ----
  ACK
  id: e11a27d3-4b86-4191-a310-12847fa79d48
  
  ^@
  ----
  
  
  == PUSH/PULL
  
negative.code: 
  ==== Header: *id*
  
  The `id` header serves for identify messages. It is mainly used by client frames.
  Frames without specified `id` does not return responses. And some frames has `id`
  as mandatory header.
  
  
  ==== Header: *content-type*
  