case_zigzag :: Assertion
case_zigzag = snd (member 4 t_zigzag) @?== a_zigzag
case_zigzag :: Assertion
case_zigzag = snd (member 4 t_zigzag) @?== a_zigzag
case_zigzag = snd (member 4 t_zigzag) @?== a_zigzag