title: How can I append the content of one map to another map?
body: <p>I have the following two maps:</p>
  
  <pre><code>map&lt; string, list &lt; string &gt; &gt; map1;
  map&lt; string, list &lt; string &gt; &gt; map2;
  </code></pre>
  
  <p>I populated <code>map1</code> with the following content:</p>
  
  <pre><code>1. kiran; c:\pf\kiran.mdf, c:\pf\kiran.ldf
  2. test;  c:\pf\test.mdf, c:\pf\test.mdf
  </code></pre>
  
  <p>Then I copied the content of <code>map1</code> into <code>map2</code> as follows:</p>
  
  <pre><code>map2 = map1;
  </code></pre>
  
  <p>Then I filled <code>map1</code> again with the following new content:</p>
  
  <pre><code>1. temp; c:\pf\test.mdf, c:\pf\test.ldf
  2. model; c:\model\model.mdf, c:\pf\model.ldf
  </code></pre>
  
  <p>Now I have to append this content to <code>map2</code>. I cannot use <code>map2 = map1;</code>, because this will overwrite the existing content in <code>map2</code>. So, how can I do this?</p>