set <State*> move(set<State*>& states, char c) {
	set<State*> ret;
	stack <State*> states_stack;
	for (State *state : states)
		states_stack.push(state);
	while (!states_stack.empty()) {
		State* curr_state = states_stack.top();
		states_stack.pop();
		map<char, vector<State*> >& transitions = curr_state->get_transitions();
		map<char, vector<State*> >::iterator start = transitions.find(c);
		if(start != transitions.end())
			for (State * s : start->second)
				ret.insert(s->get_epsilon_closure().begin(), s->get_epsilon_closure().end());
	}
	return ret;
}