@pimms.param<EOL><INDENT>def cache_delete(d):<DEDENT>
if d in [True,False,Ellipsis]: return d<EOL>raise ValueError('<STR_LIT>')<EOL>
filemap.cache_delete is the setting used to decide whether to delete the cache directory at
system exit. If Ellipsis (the default), then deletes any temporary directory created;
otherwise does as this variable instructs.