Goal:
    G : t  z : Z  le : z <= 0
  ============================
   (Some z = Some z)


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 := Some z = Some z
of type
constr of type tacvalue