list1 = [1,2,3,4,5,6]
list2 = [3, 5, 7, 9]
list(set(list1).intersection(list2))
list1 = ['little','blue','widget']
list2 = ['there','is','a','little','blue','cup','on','the','table']
list3 = set(list1)&set(list2)
list4 = sorted(list3, key = lambda k : list1.index(k))