code: def inspect_last(self, stream, only_allocated=False):
          
  
          if only_allocated:
              found = False
              for walker in self._virtual_walkers:
                  if walker.matches(stream):
                      found = True
                      break
  
              if not found:
                  raise UnresolvedIdentifierError("inspect_last could not find an allocated virtual streamer for the desired stream", stream=stream)
  
          if stream in self._last_values:
              return self._last_values[stream]
  
          raise StreamEmptyError(u"inspect_last called on stream that has never been written to", stream=stream)
docs: Return the last value pushed into a stream.
  
          This function works even if the stream is virtual and no
          virtual walker has been created for it.  It is primarily
          useful to aid in debugging sensor graphs.
  
          Args:
              stream (DataStream): The stream to inspect.
              only_allocated (bool): Optional parameter to only allow inspection
                  of allocated virtual streams.  This is useful for mimicking the
                  behavior of an embedded device that does not have a _last_values
                  array.
  
          Returns:
              IOTileReading: The data in the stream
  
          Raises:
              StreamEmptyError: if there has never been data written to
                  the stream.
              UnresolvedIdentifierError: if only_allocated is True and there has not
                  been a virtual stream walker allocated to listen to this stream.