DFS

graph1 = {
 'A': set(['B', 'C']),
 'B': set(['A', 'D', 'E']),
 'C': set(['A', 'F']),
 'D': set(['B']),
 'E': set(['B', 'F']),
 'F': set(['C', 'E']),
}
def dfs(graph, node, visited):
 if node not in visited:
     visited.append(node)
     for neighbor in graph[node]:
         dfs(graph, neighbor, visited)
 return visited
visited = dfs(graph1, 'A', [])
print(visited)
