code: def is_single_value(start_time, end_time, freq, region: str = REG_CN):
      """Is there only one piece of data for stock market.
  
      Parameters
      ----------
      start_time : Union[pd.Timestamp, str]
          closed start time for data.
      end_time : Union[pd.Timestamp, str]
          closed end time for data.
      freq :
      region: str
          Region, for example, "cn", "us"
      Returns
      -------
      bool
          True means one piece of data to obtain.
      """
      if region == REG_CN:
          if end_time - start_time < freq:
              return True
          if (
              start_time.hour == 11
              and start_time.minute == 29
              and start_time.second == 0
          ):
              return True
          if (
              start_time.hour == 14
              and start_time.minute == 59
              and start_time.second == 0
          ):
              return True
          return False
      elif region == REG_TW:
          if end_time - start_time < freq:
              return True
          if (
              start_time.hour == 13
              and start_time.minute >= 25
              and start_time.second == 0
          ):
              return True
          return False
      elif region == REG_US:
          if end_time - start_time < freq:
              return True
          if (
              start_time.hour == 15
              and start_time.minute == 59
              and start_time.second == 0
          ):
              return True
          return False
      else:
          raise NotImplementedError(
              f"please implement the is_single_value func for {region}"
          )
  
imports: import bisect
  from datetime import datetime, time, date, timedelta
  from typing import List, Optional, Tuple, Union
  import functools
  import re
  import pandas
  from qlib.config import C
  from qlib.constant import REG_CN, REG_TW, REG_US
label_desc: Use image node_id 2 for calling a global function with example usage: is_single_value(start_time, end_time, freq, region) and returns: False, True, True, True, False, True, True, False, True, True