message Student {
	required string name = 1;
	required int32 id = 2;
	optional string email = 3;

	enum PhoneType {
		MOBILE = 0;
		HOME = 1;
		WORK = 2;
	}

	message PhoneNumber {
		required string number = 1;
		optional PhoneType type = 2 [default = HOME];
	}

	repeated PhoneNumber phone = 4;
}

message Classroom {
	repeated Student student = 1;
}