code: def convert_num_to_str_freq(freq_num, initial_time_stamp):
      """Convert numeric frequencies into frequency tags
  
      Parameters
      ----------
          freq_num : int
              numeric values of delta in ms
          initial_time_stamp : str
              initial time stamp of data
  
      Returns
      -------
          str
              frequency tag
      """
      aux_ts = pd.date_range(
          initial_time_stamp,
          periods=100,
          freq=pd.to_timedelta(freq_num),
      )
      freq_str = pd.infer_freq(aux_ts)
      return freq_str
  
imports: from __future__ import annotations
  import logging
  import math
  from collections import OrderedDict
  from dataclasses import dataclass
  from typing import TYPE_CHECKING, List, Optional, Tuple
  import numpy
  import pandas
label_desc: Use image node_id 27 for calling a global function with example usage: convert_num_to_str_freq(freq_num, initial_time_stamp) and returns: freq_str