class_docstr: Handles/stores incoming dataset and provides window-based statistics.
  
  .. testcode::
      :skipif: True
  
      win_stats = WindowStat("level", 3)
      win_stats.push(5.0)
      win_stats.push(7.0)
      win_stats.push(7.0)
      win_stats.push(10.0)
      # Expect 8.0 as the mean of the last 3 values: (7+7+10)/3=8.0
      print(win_stats.mean())
  
  .. testoutput::
  
      8.0
code: def stats(self):
      return {
          self.name + "_count": int(self.count),
          self.name + "_mean": self.mean(),
          self.name + "_std": self.std(),
          self.name + "_quantiles": self.quantiles(),
      }
  
file_path: ray/python/ray/rllib/utils/metrics/window_stat.py
imports: import numpy
label_desc: Use image node_id 6 for calling the WindowStat obj's underlying member method code with example usage: obj.stats() and returns: dict