∀ {w : ℕ} (assign : Std.Tactic.BVDecide.BVExpr.Assignment) (n : ℕ) (rhs : Std.Tactic.BVDecide.BVExpr n)
  (lhs : Std.Tactic.BVDecide.BVExpr w),
  Std.Tactic.BVDecide.BVExpr.eval assign (lhs.shiftLeft rhs) =
    Std.Tactic.BVDecide.BVExpr.eval assign lhs <<< Std.Tactic.BVDecide.BVExpr.eval assign rhs