code: def str_lower(batch: Union[str, list, tuple]):
      """Recursively search for strings in a list and convert them to lowercase
  
      Args:
          batch: a string or a list containing strings at some level of nesting
  
      Returns:
          the same structure where all strings are converted to lowercase
      """
      if isinstance(batch, str):
          return batch.lower()
      else:
          return list(map(str_lower, batch))
  
label_desc: Use image node_id 1 for calling a global function with example usage: str_lower(batch) and returns: batch, list