DFS

graph = {'A' : set(['G','B']),
	'B' : set(['C','D','A']),
	'C' : set(['F','D','B']),
	'D' : set(['B','C']),
	'E' : set(['F']),
	'F' : set(['E','C']),
	'G' : set(['A']),
	}
	print (graph)

def depth_first_search(graph, start_node):

    visited_neighbours = set()

    neighbours = [start_node] 

    while (len(neighbours) != 0):

        neighbour = neighbours.pop() 

        if neighbour not in visited_neighbours:

            visited_neighbours.add(neighbour)

            new_prospected_neighbours = graph[neighbour]

            new_neighbours = new_prospected_neighbours - visited_neighbours

            neighbours.extend(new_neighbours)

    return visited_neighbours         

depth_first_search(graph, 'A')