title: How would I initialize an empty relation and add elements to it in Rascal?
body: <p>As simple as it seems, how do I initialize an empty relation (of type say, [str,int]), then add new elements to it? An approximate Rascal code:</p>
  
  <pre><code>rel[str,int] myReln={};
  
  myReln.add(&lt;"a",1&gt;);
  </code></pre>
  
  <p>Samples for remove/modify operations would also be appreciated. </p>