def dfs(self, s, t, visited):
        if s == t:
            return True

        visited.add(s)
        for nbr in s.neighbors:
            if nbr not in visited:
                if self.dfs(nbr, t, visited):
                    return True

        return False
pre-check
dataset/ETHPy150Open algorhythms/LintCode/Route Between Two Nodes in Graph.py/Solution.dfs