∀ {α : Type u_1} (xss : Array (Array α)) (_x : (_ : ℕ) ×' Array α),
  Lean.Elab.Structural.allCombinations.go._unary✝ xss _x =
    PSigma.casesOn _x fun i acc =>
      if h : i < xss.size then
        Array.flatMap (fun x => Lean.Elab.Structural.allCombinations.go._unary✝¹ xss ⟨i + 1, acc.push x⟩) xss[i]
      else #[acc]