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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def save(self, acl=None, client=None):
 """Save this ACL for the current bucket. If :attr:`user_project` is set, bills the API request to that project. :type acl: :class:`google.cloud.storage.acl.ACL`, or a compatible list. :param acl: The ACL object to save. If left blank, this will save current entries. :type client: :class:`~google.cloud.storage.client.Client` or ``NoneType`` :param client: Optional. The client to use. If not passed, falls back to the ``client`` stored on the ACL's parent. """

        if acl is None:
            acl = self
            save_to_backend = acl.loaded
        else:
            save_to_backend = True

        if save_to_backend:
            self._save(acl, None, client)