  It should either be issued when the  last  string  has  been sent
       to  the  server using <a class="xref" href="libpq-copy.html#LIBPQ-PQPUTLINE"><code class="function">PQputline</code></a> or when the
       last string has been  received  from  the  server using
       <code class="function">PQgetline</code>.  It must be issued or the server
       will get <span class="quote">“<span class="quote">out of sync</span>”</span> with  the client.   Upon return
       from this function, the server is