def get_top_namespace(node):
    """Return the top namespace of the given node

    If the node has not namespace (only root), ":" is returned.
    Else the top namespace (after root) is returned

    :param node: the node to query
    :type node: str
    :returns: The top level namespace.
    :rtype: str
    :raises: None
    """
    name = node.rsplit("|", 1)[-1]  # get the node name, in case we get a dagpath
    name = name.lstrip(":")  # strip the root namespace
    if ":" not in name:  # if there is no namespace return root
        return ":"
    else:
        # get the top namespace
        return name.partition(":")[0]