- neue prefx und postfix methoden

            self._xml_attr = OrderedDict()

        return self._xml_attr

    def get_attr(self, attribute: str, default: str) -> str:

        """

        Returns the value of 'attribute' if attribute exists. If not, the

        default value is returned. This function has the same semantics

        as `node.attr.get(attribute, default)`, but with the advantage then

        other than `node.attr.get` it does not automatically create an

        attribute dictionary on (first) access.

        :param attribute: The attribute, the value of which shall be looked up

        :param default:   A default value that is returned, in case attribute

                          does not exist.

        :return: str

        """

        if self.has_attr():

            return self.attr.get(attribute, default)

        return default

    def compare_attr(self, other: 'Node') -> bool:

        """

        Returns True, if `self` and `other` have the same attributes with the

            str(result)

class TestNodeFind():

    """Test the select_if-functions of class Node.

class TestNodeFind:

    """Test the item-access-functions of class Node.

    """

    def test_find(self):

        tree = parse_sxpr('(a (b X) (X (c d)) (e (X F)))')

        assert tree[0].equals(parse_sxpr('(b X)'))

        assert tree[2].equals(parse_sxpr('(e (X F))'))

        assert tree[-1].equals(parse_sxpr('(e (X F))'))

        try:

            node = tree[3]

            assert False, "IndexError expected!"