Falderal Test: no functionality
-------------------------------

Since no functionality is specified for these tests,
`falderal` should exit with an exception.

    -> Functionality "Cat" is implemented by
    -> shell command "python3 cat.py"

Cat cats.

    | meow
    = meow

    | purr
    | prrr
    | prreow
    = purr
    = prrr
    = prreow