Goal:
    z : Z  z0 : Z  H : False  H0 : True
  ============================
   True


DEBUG:Going to execute:
constructor 1
Level 3: evaluation returns
<coq-core.plugins.tauto::is_unit_or_eq@0>
where
tauto_flags := 
of type
tauto_flags
X1 := True
of type
constr of type tacvalue