def map_keys_to_values_list(k_lst, v_lst):
    just_the_keys = {}
    i = 0
    ezerlist = []


    for value in k_lst:
        tuple = (k_lst[i], v_lst[i])
        i +=1
        if just_the_keys.has_key(value):
            if len(ezerlist) == 1:
                ezerlist.append(just_the_keys[value])
            ezerlist.append(tuple[1])
            ezerlist.append(just_the_keys[tuple[0]])
            just_the_keys[tuple[0]] = ezerlist
            ezerlist = []
        elif not just_the_keys.has_key(value):
            just_the_keys[value] = tuple[1]
        else:
            ezerlist.append(tuple[1])
            ezerlist == []


    return just_the_keys


k_lst = ["a", "b", "c", "a", "a", "a", "c"]
v_lst = [1, 2, 3, 1, 15, 6, 7]


print map_keys_to_values_list(k_lst, v_lst)