code: def process(self, rpc_executor, mark_streamer=None):
          
  
          if self.func is None:
              raise ProcessingFunctionError('No processing function set for node', stream=self.stream)
  
          results = self.func(*[x[0] for x in self.inputs], rpc_executor=rpc_executor, mark_streamer=mark_streamer)
          if results is None:
              results = []
  
          return results
docs: Run this node's processing function.
  
          Args:
              rpc_executor (RPCExecutor): An object capable of executing RPCs
                  in case we need to do that.
              mark_streamer (callable): Function that can be called to manually
                  mark a streamer as triggered by index.
  
          Returns:
              list(IOTileReading): A list of IOTileReadings with the results of
                  the processing function or an empty list if no results were
                  produced