has_init :: Loc -> Loc -> Bool
has_init (Loc l2) (Loc l1) = take (length l1) l2 == l1
has_init :: Loc -> Loc -> Bool
has_init (Loc l2) (Loc l1) = take (length l1) l2 == l1
has_init (Loc l2) (Loc l1) = take (length l1) l2 == l1