def tst1 : 0 + 1 = 1 := rfl
def tst2 : 2 + 3 = 5 := rfl
def tst3 : 4 + 3 = 7 := rfl
def tst4 : 0 + 3 = 3 := rfl
def tst5 : 1 + 3 = 4 := rfl
def tst6 : 100 + 100 = 200 := rfl