class_docstr: A map-to-arrays dict, with deterministic Reservoir Sampling.
  
  Store each reservoir bucket by key, and each bucket is a list sampling
  with reservoir algorithm.
docstr: Get items with tag 'run_tag'
  
  For usage habits of VisualDL, actually call self._get_items()
  
  Args:
      run: Identity of one tablet.
      tag: Identity of one record in tablet.
  
  Returns:
      One bucket in reservoir buckets by run and tag.
docstr_tok: ["Get","items","with","tag","'run_tag'","For","usage","habits","of","VisualDL",",","actually","call","self._get_items","(",")","Args",":","run",":","Identity","of","one","tablet",".","tag",":","Identity","of","one","record","in","tablet",".","Returns",":","One","bucket","in","reservoir","buckets","by","run","and","tag","."]
code: def get_items(self, run, tag):
      """Get items with tag 'run_tag'
  
      For usage habits of VisualDL, actually call self._get_items()
  
      Args:
          run: Identity of one tablet.
          tag: Identity of one record in tablet.
  
      Returns:
          One bucket in reservoir buckets by run and tag.
      """
      key = run + "/" + tag
      return self._get_items(key)
  
imports: import collections
  import random
  import threading
label_desc: Use image node_id 8 for calling the Reservoir obj's underlying member method code with example usage: obj.get_items(run, tag) and returns: self