code: def follow(self, gpid, callback=None, callback_parsed=None):
          
          if callback_parsed:
              callback = self._client._get_parsed_feed_callback(callback_parsed, callback)
          return self.__sub(R_FEED, gpid, callback=callback)
docs: Create a subscription (i.e. follow) a Feed/Point with a global point id (gpid) and a feed data callback
  
          Returns a new [RemoteFeed](RemotePoint.m.html#IoticAgent.IOT.RemotePoint.RemoteFeed)
          object or the existing one if the subscription already exists - OR -
  
          Raises [IOTException](./Exceptions.m.html#IoticAgent.IOT.Exceptions.IOTException)
          containing the error if the infrastructure detects a problem
  
          Raises [LinkException](../Core/AmqpLink.m.html#IoticAgent.Core.AmqpLink.LinkException)
          if there is a communications problem between you and the infrastructure
  
          `gpid` (required) (uuid) global id of the Point you want to follow `-OR-`
  
          `gpid` (required) (lid,pid) tuple of `(thing_localid, point_localid)` for local subscription
  
          `callback` (optional) (function reference) callback function to invoke on receipt of feed data.
          The callback receives a single dict argument, with keys of:
  
              #!python
              'data' # (decoded or raw bytes)
              'mime' # (None, unless payload was not decoded and has a mime type)
              'pid'  # (the global id of the feed from which the data originates)
              'time' # (datetime representing UTC timestamp of share)
  
          `callback_parsed` (optional) (function reference) callback function to invoke on receipt of feed data. This is
          equivalent to `callback` except the dict includes the `parsed` key which holds the set of values in a
          [PointDataObject](./Point.m.html#IoticAgent.IOT.Point.PointDataObject) instance. If both
          `callback_parsed` and `callback` have been specified, the former takes precedence and `callback` is only called
          if the point data could not be parsed according to its current value description.
  
          `NOTE`: `callback_parsed` can only be used if `auto_encode_decode` is enabled for the client instance.