<span class="p">)</span><span class="w">                </span><span class="c">! length of input string</span>
<span class="c">!-----------------------------------------------------------------------------------------------------------------------------------</span>
<span class="w">   </span><span class="c">! find beginning of token</span>
<span class="w">   </span><span class="n">token_start</span><span class="o">=</span><span class="mi">1</span><span class="w"></span>
<span class="w">   </span><span class