Clone an undirected graph. Each node in the graph contains a label and a list of its neighbors.

How we serialize an undirected graph:

Nodes are labeled uniquely.

We use `#`

as a separator for each node, and `,`

as a separator for node label and each neighbor of the node.

As an example, consider the serialized graph `{0,1,2#1,2#2,2}`

.

The graph has a total of three nodes, and therefore contains three parts as separated by `#`

.

- First node is labeled as 0. Connect node 0 to both nodes 1 and 2.
- Second node is labeled as 1. Connect node 1 to node 2.
- Third node is labeled as 2. Connect node 2 to node 2 (itself), thus forming a self-cycle.

Visually, the graph looks like the following:

```
1
/ \
/ \
0 --- 2
/ \
\_/
```

Example

return a deep copied graph.