code: def dump_constants(self):
          
  
          constants = []
  
          for walker in self._virtual_walkers:
              if not walker.selector.inexhaustible:
                  continue
  
              constants.append((walker.selector.as_stream(), walker.reading))
  
          return constants
docs: Dump (stream, value) pairs for all constant streams.
  
          This method walks the internal list of defined stream walkers and
          dumps the current value for all constant streams.
  
          Returns:
              list of (DataStream, IOTileReading): A list of all of the defined constants.