code: def error(self, msg, previous=False):
          
          token = self.tokens[self.current_token - 1]
          line_no = self.line
          if previous:
              line_no -= 1
          line = self.raw[line_no]
          position = token["start"] - self.line_start
          if previous:
              position = len(line) + 2
          raise ParseException(msg, line, line_no + 1, position, token["value"])
docs: Raise a ParseException.
          We provide information to help locate the error in the config to allow
          easy config debugging for users.  previous indicates that the error
          actually occurred at the end of the previous line.