Goal:
    A : Type  l : list A  hd : A  tl : list A
  ============================
   (Some hd = Some hd ∧ tl = tl)


DEBUG:Going to execute:
solve [ split; do_ccl ]
Level 1: Backtrace:

Failed to progress.
Level 0: Backtrace:

Failed to progress.
Level 0: Backtrace:

Failed to progress.
Level 0: Backtrace:

Failed to progress.
Level 0: Backtrace:

Failed to progress.