def storage(self, *, resource=None):
        """ Get an instance to handle file storage (OneDrive / Sharepoint)
        for the specified account resource

        :param str resource: Custom resource to be used in this drive object
         (Defaults to parent main_resource)
        :return: a representation of OneDrive File Storage
        :rtype: Storage
        :raises RuntimeError: if protocol doesn't support the feature
        """
        if not isinstance(self.protocol, MSGraphProtocol):
            # TODO: Custom protocol accessing OneDrive/Sharepoint Api fails here
            raise RuntimeError(
                'Drive options only works on Microsoft Graph API')

        return Storage(parent=self, main_resource=resource)