Goal:
    _z_ : VSet.t
  ============================
   (VSet.Equal _z_ _z_)


DEBUG:Going to execute:
clear H
Level 1: Backtrace:

In environment
_z_ : VSet.t
The term "VSet.t" has type "Type" while it is expected to have type 
"Prop" (universe inconsistency: Cannot enforce VSet.t.u0 <= Prop).