code: protected function getLocaleFromInput($input = null): string
      {
          if ($input instanceof Locale) {
              $input = $input->getCode();
          }
  
          if (null === $input) {
              return $this->localeCode;
          }
  
          if ($this->sys->getLocale() && $input !== $this->sys->getLocale()) {
              throw new \InvalidArgumentException(\sprintf(
                  'Entry with ID "%s" was built using locale "%s", but now access using locale "%s" is being attempted.',
                  $this->sys->getId(),
                  $this->sys->getLocale(),
                  $input
              ));
          }
  
          if (!\in_array($input, $this->localeCodes, true)) {
              throw new \InvalidArgumentException(\sprintf(
                  'Trying to use invalid locale "%s", available locales are "%s".',
                  $input,
                  \implode(', ', $this->localeCodes)
              ));
          }
  
          return $input;
      }
docs: @param Locale|string|null $input
  
  @throws \InvalidArgumentException when $locale is not one of the locales supported by the space
  
  @return string