def _alert_malformed(self, msg, row_num):
if self.error_bad_lines:<EOL><INDENT>raise ParserError(msg)<EOL><DEDENT>elif self.warn_bad_lines:<EOL><INDENT>base = '<STR_LIT>'.format(row_num=row_num)<EOL>sys.stderr.write(base + msg + '<STR_LIT:\n>')<EOL><DEDENT>
Alert a user about a malformed row.

If `self.error_bad_lines` is True, the alert will be `ParserError`.
If `self.warn_bad_lines` is True, the alert will be printed out.

Parameters
----------
msg : The error message to display.
row_num : The row number where the parsing error occurred.
          Because this row number is displayed, we 1-index,
          even though we 0-index internally.