code: def load_simdata(self, idx: int) -> None:
          
          if self._sim_ramflag:
              self.sim[0] = self._sim_array[idx]
          elif self._sim_diskflag:
              raw = self._sim_file.read(8)
              self.sim[0] = struct.unpack('d', raw)
docs: Load the next sim sequence value (of the given index).