code: def get_raw_history(self, item=None, nb=0):
          
          s = self.stats_history.get(nb=nb)
          if item is None:
              return s
          else:
              if item in s:
                  return s[item]
              else:
                  return None
docs: Return the history (RAW format).
  
          - the stats history (dict of list) if item is None
          - the stats history for the given item (list) instead
          - None if item did not exist in the history