Using flush_output/1
on a compressed stream causes a
Z_SYNC_FLUSH on the stream. Using close/1
on a compressed stream causes a Z_FINISH on the stream. If
the stream uses the gzip format, a gzip compatible
footer is written to the stream. If close_parent is set
(default) the underlying stream is closed too. Otherwise it remains open
and the user can continue communication in non-compressed format or
reopen the stream for compression using zopen/3.