val it : string seq seq =
  seq
    [seq ["abel"; "able"; "bale"; "bela"; "elba"];
     seq ["alger"; "glare"; "lager"; "large"; "regal"];
     seq ["angel"; "angle"; "galen"; "glean"; "lange"];
     seq ["caret"; "carte"; "cater"; "crate"; "trace"];
     seq ["elan"; "lane"; "lean"; "lena"; "neal"];
     seq ["evil"; "levi"; "live"; "veil"; "vile"]]