A simple DFS example

dfs.py

import graphviz

g = {
        'A': ['B', 'C', 'D', 'F'],
        'B': ['C', 'D'],
        'D': ['A', 'C'],
        'C': [],
        'E': ['C', 'G'],
        'F': ['A', 'C'],
        'G': ['E']
        }

def dfs(g, cur, mark, tree):
    mark[cur] = True
    for succ in g[cur]:
        if not mark[succ]:
            tree.edge(cur, succ)
            dfs(g, succ, mark, tree)

tree = graphviz.Digraph(name='g')
mark = { v : False for v in g.keys() }
dfs(g, 'A', mark, tree)
tree.save(filename='g.dot')