exact he.2 <| hcl.subset (M.mem_cl_of_mem (mem_insert e F))
case refine_2
α : Type u_1
M : Matroid α
I F X Y F' F₀ F₁ F₂ P L H H₁ H₂ H' B C K : Set α
e f : α
hF : M.Flat F
he : e ∈ M.E \ F
hcl : M.cl (insert e F) = F
hfF : f ∈ F
⊢ False
no goals