
    cs <- c(23, 19, 30, 22, 23, 29, 35, 36, 33, 25)
    ts <- c(430, 430, 333, 410, 390, 377, 325, 310, 328, 375)
    mod <- lm(ts ~ cs)
    s <- summary(mod)


    # regress `ts` solely on `cs`. Store the result in `mod_ni`.


    # regress `ts` solely on `cs`. Store the result in `mod_ni`.
    mod_ni <- lm(ts ~ cs - 1) 
    # or 
    lm(ts ~ cs + 0)


    test_predefined_objects("mod")

    test_or(
    {
      test_student_typed("ts ~ cs + 0")
    },{
      test_student_typed("ts ~ cs - 1")
    }
    )

    test_function("lm")

    test_object("mod_ni", eval=F)