∀ (initFieldPos? lastFieldTailPos? : Option String.Pos.Raw) (hasWith : Bool) (numFields : ℕ)
  (openingPos leaderPos leaderTailPos closingPos : String.Pos.Raw),
  sizeOf
      { initFieldPos? := initFieldPos?, lastFieldTailPos? := lastFieldTailPos?, hasWith := hasWith,
        numFields := numFields, openingPos := openingPos, leaderPos := leaderPos, leaderTailPos := leaderTailPos,
        closingPos := closingPos } =
    1 + sizeOf initFieldPos? + sizeOf lastFieldTailPos? + sizeOf hasWith + sizeOf numFields + sizeOf openingPos +
          sizeOf leaderPos +
        sizeOf leaderTailPos +
      sizeOf closingPos