" class="symbol"><i><span class="symbol">defun</span></i></a> rotate <span class="paren2">(<span class="paste">input-pathname output-pathname</span>)</span><br>&nbsp;&nbsp;<span class="string">"Read a PNG image, rotate it 90 degrees, and write it to a new file."</span><br>&nbsp;&nbsp;<span class="paren2">(<span class="paste"><a href="http://www.lispworks.com/reference/HyperSpec/Body/s_let_l.htm" class="symbol"><i><span class="symbol">let*</span></i></a> <span class="paren3">(<span class="paste"><span class=