Exception has occurred: KeyError 'h' File "C:\Users\username\Downloads\test.py", line 19, in dfs, how to fix?

Question

# Python dictionary to act as an adjacency list
graph = {
  'a' : ['b','c'],
  'b': ['d', 'e'],
  'd': ['h','i'],
  'e': ['j', 'k'],
  'c' : ['f','g'],
  'g': ['l','m']
}

visited = [] # List of visited nodes of graph.
def dfs(visited, graph, node):
    
    if node not in visited:
        visited.append(node)
    

    for neighbor in graph[node]:
        dfs(visited, graph, neighbor)
    print(node)

# Driver Code
print("Following is the Depth-First Search")
dfs(visited, graph, "a")
print("visited=",visited)

How do I fix this error.

This is a tree. To visualize that you need to know that a has two child b and c.

b has 2 child d and e

d has 2 child h and i

e has 2 child j and k and so on.

I ran a similar code but with numbers in those graph like 7,8 etc instead of a,b,c. It ran perfectly. But here in this case it is not running. Can you debug this