code: def fiscal_code(self, gender: Optional[Gender] = None) -> str:
          
          code = ''.join(self.random.choices(string.ascii_uppercase, k=6))
  
          code += self.random.custom_code(mask='##')
  
          month_codes = self._data['fiscal_code']['month_codes']
          code += self.random.choice(month_codes)
  
          birth_day = self.random.randint(101, 131)
          self._validate_enum(gender, Gender)
          if gender == Gender.FEMALE:
              birth_day += 40
          code += str(birth_day)[1:]
  
          city_letters = self._data['fiscal_code']['city_letters']
          code += self.random.choice(city_letters)
          code += self.random.custom_code(mask='###@')
  
          return code
docs: Return a random fiscal code.
  
          :param gender: Gender's enum object.
          :return: Fiscal code.
  
          Example:
              RSSMRA66R05D612U