def get_nodes_by_property_key(self, key):
        ret = set()
        for _nd in core.get_nodes_by_property_key(self.cursor, key):
            node = self.node_factory(self, _nd.id)
            ret.add(node)
        return ret
Get a set of nodes which have a property named ``key`` in their
dataset/ETHPy150Open conceptsandtraining/libtree/libtree/transaction.py/Transaction.get_nodes_by_property_key