Goal:
  
  m : t
  a : t
  l : list t
  IHl : forall n : t, fold_left max l n = m -> n = m \/ In m l
  n : t
  H : In m l
  ============================
   (In m l)


DEBUG:Going to execute:
(solve [ do_atom | use_hyps; do_ccl ]) ||
             fail "Cannot solve this goal"