'Adds a new root provider to the tree.'

def new_root(self, name, uuid, generation):

    with self.lock:
        if (self._find_with_lock(uuid) is not None):
            raise ValueError((_('Provider    %s    already    exists    as    a    root.') % uuid))
        p = _Provider(name, uuid, generation)
        self.roots.append(p)
        return p
