Because `DataSet` has several elements that need to be typed, there is no default way to just serialize it. Instead, you need to stuff it into a `SerializableDataSet` first. The point of this is to specify lists of field and cell types that might be encountered. This, however, is of dubious value anymore. Instead, there should be a precompiled function that serializes a `DataSet` for default types, and `SerializableDataSet` should be deprecated.