Goal:
    z : Z  z0 : Z  H : (z <= z0)%Z
  ============================
   ((z0 <= z)%Z -> Some z = Some z0)


DEBUG:Going to execute:
try do_atom
Level 2: Backtrace:

The type of H is not inductive.
Level 2: Backtrace:

No applicable tactic.
Level 1: evaluation returns
idtac of type tacvalue