∀ {n : ℕ} (f : Std.Tactic.BVDecide.LRAT.Internal.DefaultFormula n)
  (c : Std.Tactic.BVDecide.LRAT.Internal.DefaultClause n),
  (match c.isUnit with
      | none =>
        { clauses := f.clauses.push (some c), rupUnits := f.rupUnits, ratUnits := f.ratUnits,
          assignments := f.assignments }
      | some (l, true) =>
        { clauses := f.clauses.push (some c), rupUnits := f.rupUnits, ratUnits := f.ratUnits,
          assignments := f.assignments.modify (↑l) Std.Tactic.BVDecide.LRAT.Internal.Assignment.addPosAssignment }
      | some (l, false) =>
        { clauses := f.clauses.push (some c), rupUnits := f.rupUnits, ratUnits := f.ratUnits,
          assignments :=
            f.assignments.modify (↑l) Std.Tactic.BVDecide.LRAT.Internal.Assignment.addNegAssignment }).ratUnits =
    f.ratUnits