->                                               ->
  expect avg s (                                   expect avg s (
                 [ x = 2 ]                                        [ x = -0.6 ]
                 ' x = avg { 1, 2, 3 }                            ' x = avg { -1, 2.5, -3.3 }
               )                                                )
  ' s = 'works with list of integer numbers'       ' s = 'works with list of float+- numbers'
;                                                ;
