def get_child_node(self, key, reload=False):
        if key not in self._children or reload == True:
            self._children[key] = self.load_child_node(key)
        return self._children[key]
Return the child node for a given key.  Create if necessary.
dataset/ETHPy150Open AnyMesh/anyMesh-Python/example/urwid/treetools.py/ParentNode.get_child_node