code: async function setPreferredMcpRegionalSettings(accessToken, languageTag) {
      let regionalSettings = getValidLanguageTagOrThrow(languageTag);
  
      return mcpCustomizr.putSettings(accessToken, {
          regionalSettings: regionalSettings,
      });
  }
docs: Update the preferred regional format in Customizr
  @param {string} accessToken - Access token to use to call Customizr
  @param {string} languageTag - RFC 4656 compliant language code (eg. en, en-US)
  @return {Promise<void>}