deque.py

graph = {}
graph["you"] = ["alice", "bob", "claire"]
graph["bob"] = ["anuj", "peggy"]
graph["alice"] = ["peggy"]
graph["claire"] = ["thom", "jonny"]
graph["anuj"] = []
graph["peggy"] = []
graph["thom"] = []
graph["jonny"] = []


def person_is_seller(name):
    return name[-1] == 'm'
from collections import deque
search_queue = deque()
search_queue += graph["you"]
searched = []
def search(name):
 search_queue = deque()
 search_queue+= graph[name]
while search_queue:                                                                                                                                     
    person = search_queue.popleft()
    if not person in searched:  
        if person_is_seller(person):
            print(person+" is the person you want")
        else:
            search_queue += graph[person]
            searched.append(person)


print(search('you'))