t;foo&quot; ) );&nbsp; // 
(1)<br>
<br>
remove_all( &quot;foo&quot; );<br>
assert( !exists( &quot;foo&quot; ) );&nbsp; // (2)<br>
<br>
assert( is_directory( &quot;foo&quot; ) == is_directory( &quot;foo&quot; ) ); // 
(3)</code></p>
</blockquote>
<p>(1) will fail if a non-existent &quot;foo&quot; comes into existence, or an 
existent &quot;foo&quot; is removed, between the first and second call to <i>exists()</i>. 
This could happen if, during the execution of the example code, another thread, 
process, or c