def test_tag_nodes_single_tag(self):
    tagged_node = node(identity, 'input', 'output', tags='hello').tag('world')
    assert ('hello' in tagged_node.tags)
    assert ('world' in tagged_node.tags)
    assert (len(tagged_node.tags) == 2)
def test_tag_nodes_single_tag(self):
    tagged_node = node(identity, 'input', 'output', tags='hello').tag('world')
    assert ('hello' in tagged_node.tags)
    assert ('world' in tagged_node.tags)
    assert (len(tagged_node.tags) == 2)