code: def check_for_period_error(data, period):
      
      period = int(period)
      data_len = len(data)
      if data_len < period:
          raise Exception("Error: data_len < period")
docs: Check for Period Error.
  
      This method checks if the developer is trying to enter a period that is
      larger than the data set being entered. If that is the case an exception is
      raised with a custom message that informs the developer that their period
      is greater than the data set.