def month_number(self, name: str) -> Optional[int]:
        """Returns the month number for a month specified by name or abbreviation.

        :param name: the month name or abbreviation.

        """

        if self._month_name_to_ordinal is None:
            self._month_name_to_ordinal = self._name_to_ordinal(self.month_names)
            self._month_name_to_ordinal.update(
                self._name_to_ordinal(self.month_abbreviations)
            )

        return self._month_name_to_ordinal.get(name)
Returns the month number for a month specified by name or abbreviation.

        :param name: the month name or abbreviation.

        
arrow/locales.py