docs: def warm(self, jittering_ratio=0.2):
          """Progressively load the previous snapshot during the day.
  
          Loading all the snapshots at once can takes a substantial amount of time. This method, if called
          periodically during the day will progressively load those snapshots one by one. Because many workers are
          going to use this method at the same time, we add a jittering to the period between load to avoid
          hammering the disk at the same time.
          """
          if self.snapshot_to_load == None:
              last_period = self.current_period - dt.timedelta(days=self.expiration-1)
              self.compute_refresh_period()
              self.snapshot_to_load = []
              base_filename = "%s/%s_%s_*.dat" % (self.snapshot_path, self.name, self.expiration)
              availables_snapshots = glob.glob(base_filename)
              for filename in availables_snapshots:
                  snapshot_period = dt.datetime.strptime(filename.split('_')[-1].strip('.dat'), "%Y-%m-%d")
                  if snapshot_period >= last_period:
                      self.snapshot_to_load.append(filename)
                      self.ready = False
  
          if self.snapshot_to_load and self._should_warm():
              filename = self.snapshot_to_load.pop()
              self._union_bf_from_file(filename)
              jittering = self.warm_period * (np.random.random()-0.5) * jittering_ratio
              self.next_snapshot_load = time.time() + self.warm_period + jittering
              if not self.snapshot_to_load:
                  self.ready = True