grokking-alogrithms-breadth-first-search.py

from collections import deque

def search(name, graph):
  search_queue = deque()
  search_queue += graph[name]
  searched = []
  while search_queue:
    person = search_queue.popleft()
    if not person in searched:
      if person_is_seller(person): # or any other function
        print person + " is a mango seller"
        return True
      else:
        search_queue = += graph[person]
        searched.append(person)
  return False