You are playing the following Flip Game with your friend: Given a string that contains only these two characters: + and -, you and your friend take turns to flip two consecutive "++" into "--". The game ends when a person can no longer make a move and therefore the other person will be the winner.

Write a function to compute all possible states of the string after one valid move.


Input: s = "++++"

Note: If there is no valid move, return an empty list [].


class Solution(object):
    def generatePossibleNextMoves(self, s):
        :type s: str
        :rtype: List[str]
        if len(s) <= 1:
            return []

        res = []

        for i in range(1, len(s)):
            if s[i] == s[i - 1] == '+':
                res.append(s[:i-1] + '--' + s[i+1:])

        return res