Implements Authorizer.authorize by calling identity.allow to
        determine whether the identity is a member of the ACLs associated with
        the given operations.

def authorize(self, ctx, identity, ops):
        '''Implements Authorizer.authorize by calling identity.allow to
        determine whether the identity is a member of the ACLs associated with
        the given operations.
        '''
        if len(ops) == 0:
            # Anyone is allowed to do nothing.
            return [], []
        allowed = [False] * len(ops)
        has_allow = isinstance(identity, ACLIdentity)
        for i, op in enumerate(ops):
            acl = self._get_acl(ctx, op)
            if has_allow:
                allowed[i] = identity.allow(ctx, acl)
            else:
                allowed[i] = self._allow_public and EVERYONE in acl
        return allowed, []