class_docstr: Find appropriate date and adjust date.
class_docstr_tok: ["Find","appropriate","date","and","adjust","date","."]
docstr: Get datetime by index.
  
  Parameters
  ----------
  idx : int
      index of the calendar
docstr_tok: ["Get","datetime","by","index",".","Parameters","--","--","--","--","--","idx",":","int","index","of","the","calendar"]
code: def get(self, idx: int):
      """
      Get datetime by index.
  
      Parameters
      ----------
      idx : int
          index of the calendar
      """
      if idx is None or idx >= len(self.cals):
          return None
      return self.cals[idx]
  
imports: import bisect
  from copy import deepcopy
  import pandas
  from qlib.data import D
  from qlib.utils import hash_args
  from qlib.utils.mod import init_instance_by_config
  from qlib.workflow import R
  from qlib.config import C
  from qlib.log import get_module_logger
  from pymongo import MongoClient
  from pymongo.database import Database
  from typing import Union
  from pathlib import Path
label_desc: Use image node_id 3 for calling the TimeAdjuster obj's underlying member method code with example usage: obj.get(idx) and returns: self, None