### Tell us what’s happening:

Describe your issue in detail here.

how to solve this ?

### Your code so far

```
my_graph = {
'A': [('B', 3), ('D', 1)],
'B': [('A', 3), ('C', 4)],
'C': [('B', 4), ('D', 7)],
'D': [('A', 1), ('C', 7)]
}
/* User Editable Region */
def shortest_path(graph, start):
unvisited = []
for cat in my_graph:
unvisited.append(cat)
/* User Editable Region */
```

### Your browser information:

User Agent is: `Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36`

### Challenge Information:

Learn Algorithm Design by Building a Shortest Path Algorithm - Step 21