[Elab.step] #check fun x => m x
[Elab.step] none fun x => m x
[Elab.step] Sort _ _
[Elab.step] none m x
[Elab.step] none fun x✝ => x
[Elab.step] Sort _ _
[Elab.step] none x
fun (x : ?m) (x_1 : ?m x) => x : (x : ?m) → ?m x → ?m
[Elab.step] end