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              <p>Make the X lines draggable such that</p>

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            <div class="content"><div class='highlight'><pre>        lineDrag = (<span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-params">()</span> {</span>
          <span class="hljs-keyword">var</span> x1, x2;
          <span class="hljs-keyword">return</span> d3.behavior.drag()
            .on(<span class="hljs-string">'dragstart'</span>, <span class="hljs-function"