code: def subscribe(self, name, params, callback=None):
          
          cur_id = self._next_id()
          if callback:
              self._callbacks[cur_id] = callback
          self.send({'msg': 'sub', 'id': cur_id, 'name': name, 'params': params})
          return cur_id
docs: Subcribe to add/change/remove events for a collection
  
          Arguments:
          name - the name of the publication to subscribe
          params - params to subscribe (parsed as ejson)
  
          Keyword Arguments:
          callback - a callback function that gets executed when the subscription has completed