class_docstr: Interface for using a run index.
class_docstr_tok: ["Interface","for","using","a","run","index","."]
code: def __init__(self, path=None):
      self.path = path or var.cache_dir("runs")
      self._db = self._init_db()
      self._attr_reader = AttrReader()
      self._flag_reader = FlagReader()
      self._scalar_reader = ScalarReader(self._db)
  
imports: import logging
  import os
  import sqlite3
  from guild import run_util
  from guild import tfevent
  from guild import util
  from guild import var
label_desc: Use image node_id 1 to create a new RunIndex object  with example: obj = RunIndex(path)