def set_child_node(self, key, node):
        self._children[key]=node
log through to stderr and return what is passed in
dataset/ETHPy150Open AnyMesh/anyMesh-Python/example/urwid/treetools.py/ParentNode.set_child_node--crossover with--dataset/ETHPy150Open westurner/pyline/pyline.py/log_