code: def values(self):
          
          # if accessing and stale - update first
          if self._needupdate or self.now != self.parent.now:
              self.update(self.root.now)
          if self.root.stale:
              self.root.update(self.root.now, None)
          return self._values.loc[:self.now]
docs: TimeSeries of values.