_getValueFromPersistentStorage() {
        if (this.settings.saveValueToSessionStorage) {
            return sessionStorage.getItem(this.rawValueStorageName);
        }

        AutoNumericHelper.warning('`_getValueFromPersistentStorage()` is called but `settings.saveValueToSessionStorage` is false. There must be an error that needs fixing.', this.settings.showWarnings);

        return null;
    }
Retrieve the raw value from sessionStorage or the cookie depending on what the browser is supporting.

@returns {*}
@private