Goal:
    x2 : V.t  n2 : Z  y2 : V.t
  ============================
   ((x2, n2, y2) = (x2, n2, y2))


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 := (x2, n2, y2) = (x2, n2, y2)
of type
constr of type tacvalue