public User signup(String mail, String name, String username, String password) {
		if (!TextVerifier.verifyEmail(mail) || !TextVerifier.verifyName(username, policy) || !TextVerifier.verifyPassword(password, policy) || name.equals("")) return null;
		User member = new User(mail, name, username, password, Rank.member);
		this.members.add(member);
		save();
		return member;
	}