// functions to calculate score
env.addFunction(GetPassedFunction.name, new GetPassedFunction(userCourseEnv));
env.addFunction(GetScoreFunction.name, new GetScoreFunction(userCourseEnv));
env.addFunction(GetPassedWithCourseIdFunction.name, new GetPassedWithCourseIdFunction(userCourseEnv));
env.addFunction(GetScoreWithCourseIdFunction.name, new GetScoreWithCourseIdFunction(userCourseEnv));
// units
env.addUnit("min", new MinuteUnit());
env.addUnit("h", new HourUnit());
env.addUnit("d", new DayUnit());