class_docstr: Basic in-memory dict-based object for saving Task Records.
  
  This is the first object to present the DB interface
  for logging tasks out of memory.
  
  The interface is based on MongoDB, so adding a MongoDB
  backend should be straightforward.
docstr: Find records matching a query dict, optionally extracting subset of keys.
  
  Returns dict keyed by msg_id of matching records.
  
  Parameters
  ----------
  check : dict
      mongodb-style query argument
  keys : list of strs [optional]
      if specified, the subset of keys to extract.  msg_id will *always* be
      included.
docstr_tok: ["Find","records","matching","a","query","dict",",","optionally","extracting","subset","of","keys",".","Returns","dict","keyed","by","msg_id","of","matching","records",".","Parameters","--","--","--","--","--","check",":","dict","mongodb-style","query","argument","keys",":","list","of","strs","[","optional","]","if","specified",",","the","subset","of","keys","to","extract",".","msg_id","will","*","always","*","be","included","."]
code: def find_records(self, check, keys=None):
      """Find records matching a query dict, optionally extracting subset of keys.
  
      Returns dict keyed by msg_id of matching records.
  
      Parameters
      ----------
      check : dict
          mongodb-style query argument
      keys : list of strs [optional]
          if specified, the subset of keys to extract.  msg_id will *always* be
          included.
      """
      matches = self._match(check)
      if keys:
          return [self._extract_subdict(rec, keys) for rec in matches]
      else:
          return matches
  
imports: import copy
  from copy import deepcopy
  from datetime import datetime
  from traitlets import Dict, Float, Integer, Unicode
  from traitlets.config.configurable import LoggingConfigurable
  from ..util import ensure_timezone
label_desc: Use image node_id 14 for calling the DictDB obj's underlying member method code with example usage: obj.find_records(check, keys) and returns: unknown, matches