 only tail call is the call to <tt>f</tt>.
None of the calls to <tt>g</tt> or <tt>h</tt> are tail calls.  The reference to
<tt>x</tt> is in a tail context, but it is not a call and thus is not a
tail call.
<tt>(lambda&nbsp;()<br>
&nbsp;&nbsp;(if&nbsp;(g)<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(let&nbsp;((x&nbsp;(h)))<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;x)<br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(and&nbsp;(g)&nbsp;(f))))<br>
</p>
</tt>
<blockquote><em>Note:&nbsp;&nbsp;</em>
Implementations a