code: def validate_ltsv_label(label):
      
  
      validate_null_string(label, error_msg="label is empty")
  
      match_list = __RE_INVALID_LTSV_LABEL.findall(preprocess(label))
      if match_list:
          raise InvalidCharError(
              "invalid character found for a LTSV format label: {}".format(match_list)
          )
docs: Verifying whether ``label`` is a valid
      `Labeled Tab-separated Values (LTSV) <http://ltsv.org/>`__ label or not.
  
      :param str label: Label to validate.
      :raises pathvalidate.NullNameError: If the ``label`` is empty.
      :raises pathvalidate.InvalidCharError:
          If invalid character(s) found in the ``label`` for a LTSV format label.