++- Selene                                                 ** Veronica

->                                                         (@ +-
  expect avg a s (                                             (expect avg a s (@ +- 
                   x = avg {}                                                      (# avg _' .x)
                 )                                                             ) 
  ' a = ERR_PARAMETER | ERR_EMPTY_*,                           -
    s = 'when list is empty'                                       (+ERR_PARAMETER+ERR_EMPTY_* .a)
;                                                                  ('when list is empty' .s)
                                                               )
                                                           )
