(motive : Lean.Expr → Sort u_1) →
  (__discr : Lean.Expr) →
    ((v head : Lean.Level) →
        (α β' arg s f : Lean.Expr) →
          motive ((((((Lean.Expr.const `Finset.sum [v, head]).app α).app β').app arg).app s).app f)) →
      ((x : Lean.Expr) → motive x) → motive __discr