put buffer.  Then we know that <tt>deflate()</tt> has done as much as it can with
the provided input, and that all of that input has been consumed.  We can then fall out of this
loop and reuse the input buffer.
<p>
The way we tell that <tt>deflate()</tt> has no more output is by seeing that it did not fill
the output buffer, leaving <tt>avail_out</tt> greater than zero.  However suppose that
<tt>deflate()</tt> has no more output, but just so happened to exactly fill the output buffer!
<tt>avail_out</tt> is 