00004"></a><span class="lineno">    4</span>&#160;<span class="keyword">import</span> os</div><div class="line"><a name="l00005"></a><span class="lineno">    5</span>&#160;</div><div class="line"><a name="l00006"></a><span class="lineno">    6</span>&#160;non_ligs = [<span class="stringliteral">&#39;DMS&#39;</span>, <span class="stringliteral">&#39;CL&#39;</span>, <span class="stringliteral">&#39;MG&#39;</span>, <span class="stringliteral">&#39;EDO&#39;</span>, <span class="stringliteral">&#39;PEG&#39;</spa