Python path and append

[Dan Sommers]

On Tue, 26 Apr 2016 11:51:23 +1000, Steven D'Aprano wrote:

> ... (Possible a few very old operating systems on supercomputers from
> the 1970s or 80s may have supported inserting... I seem to recall that
> VMS may have allowed that... but don't quote me.)

Some [non-supercomputer] OSes/filesystems/languages support(ed) the
notion of fixed-length records, where a file acted as if it were an
array of records.  You could, e.g., replace Record Number 3 without
disturbing Record Number 2 or Record Number 4.  In the systems I
remember like that, the records were simply ad hoc collections of
whatever you wrote, not unlike the arguments to print, and it was up to
your application to read and write the same structure.  The limitation,
of course, was that you had to declare the length up front, and that you
ended up with wasted space somewhere if a lot of your records were
"short."