+ *
+ * Seekable streams largely fall into two categories: resizable and
+ * fixed-size.
+ *
+ * #GSeekable on fixed-sized streams is approximately the same as POSIX
+ * lseek() on a block device (for example: attmepting to seek past the
+ * end of the device is an error). Fixed streams typically cannot be
+ * truncated.
+ *
+ * #GSeekable on resizable streams is approximately the same as POSIX
+ * lseek() on a normal file. Seeking past the end and writing data will
+ * usually cause the stream to resize by introducing zero bytes.