class_docstr: Manager for trading calendar
      - BaseStrategy and BaseExecutor will use it
code: def __repr__(self) -> str:
      return (
          f"class: {self.__class__.__name__}; "
          f"{self.start_time}[{self.start_index}]~{self.end_time}[{self.end_index}]: "
          f"[{self.trade_step}/{self.trade_len}]"
      )
  
imports: from __future__ import annotations
  from abc import abstractmethod
  from typing import Any, Set, Tuple, TYPE_CHECKING, Union
  import numpy
  from qlib.utils.time import epsilon_change
  import warnings
  import pandas
  from ..data.data import Cal
label_desc: Use image node_id 12 for calling the TradeCalendarManager obj's underlying member method code with example usage: obj.__repr__() and returns: str, self, str, self, str, self, str, self, str, self, str, self, str, self, str