🚀 go-pugleaf

I have a program which saves intermediate results to a file, usually but
not necessarily on SUMEX.  What I want it to do is:
(1) Check if the given file name already exists.  If it does, copy its
    contents to a temporary file.
(2) Delete the given file name.
(3) Open the (now-empty) file, and write stuff to it, and close it.
(4) Delete the temporary file.
(5) Do some other stuff, then go back to (1).

The temporary file is in case something ugly happens while the given
file name is being written.  This all works fine, with one problem:
Step (2) doesn't actually get rid of the given file, it just (apparently)
marks it as deleted, so if the above 5 steps are done, say, 10 times
I end up with 10 versions of the given file name on SUMEX.  I only
want one version.  It seems if there was some way to do an EXPUNGE on
SUMEX just after step (2) the problem would be solved.  Does anyone
know if this is possible?  Or is there some better solution that I
haven't thought of?  

Thank you very much,

John Sullivan
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