∀ (accessed modified : IO.FS.SystemTime) (byteSize : UInt64) (type : IO.FS.FileType) (numLinks : UInt64),
  sizeOf { accessed := accessed, modified := modified, byteSize := byteSize, type := type, numLinks := numLinks } =
    1 + sizeOf accessed + sizeOf modified + sizeOf byteSize + sizeOf type + sizeOf numLinks