def del_node(self, key='', node=None):
"""Delete a node.
Args:
key: key
node: node
Return:
True for success, False for fail.
"""
if node:
key = node.key()
if key == '' or key not in self.nodes:
return False
self.nodes.pop(self.nodes.index(key))
if node:
target = node
else:
target = MapDataNode.get(key)
target.del_all_connect()
target.delete()
return True
