refine ⟨fun h ↦ h.pairwise_disjoint_of_indep_subsets
  (fun _ ↦ Subset.rfl) (fun i ↦ hI.subset (subset_iUnion _ _)),
  fun h ↦ hI.skewFamily_of_disjoint_bases ?_ (fun i ↦ (hI.subset (subset_iUnion _ _)).basis_self)⟩
ι : Type u_1
α : Type u_2
M : Matroid α
B I J X X' Y Y' F : Set α
Xs Ys Js Is : ι → Set α
i j : ι
e f : α
hI : M.Indep (⋃ i, Is i)
⊢ M.SkewFamily Is ↔ Pairwise (Disjoint on Is)
ι : Type u_1
α : Type u_2
M : Matroid α
B I J X X' Y Y' F : Set α
Xs Ys Js Is : ι → Set α
i j : ι
e f : α
hI : M.Indep (⋃ i, Is i)
h : Pairwise (Disjoint on Is)
⊢ Pairwise (Disjoint on fun i => Is i)