code: def get_delta(periods, data_frequency):
      """
      Get a time delta based on the specified data frequency.
  
      Parameters
      ----------
      periods: int
      data_frequency: str
  
      Returns
      -------
      timedelta
  
      """
      return (
          timedelta(minutes=periods)
          if data_frequency == "minute"
          else timedelta(days=periods)
      )
  
file_path: catalyst/catalyst/exchange/utils/datetime_utils.py
imports: import calendar
  import math
  import re
  from datetime import datetime, timedelta, date
  import pandas
  import pytz
  from catalyst.exchange.exchange_errors import InvalidHistoryFrequencyError, InvalidHistoryFrequencyAlias
label_desc: Use image node_id 3 for calling a global function with example usage: get_delta(periods, data_frequency) and returns: unknown