title: extract content between nested parenthesis
body: <p>I want to extract between <code>ObjectUnionOf(</code> and the first closed parenthese coming after it:</p>
  
  <p><code>&lt;http://www.ifomis.org/bfo/1.1/spanScatteredTemporalRegion&gt; &lt;http://www.ifomis.org/bfo/1.1/spanConnectedTemporalRegion&gt;</code></p>
  
  <p>From</p>
  
  <pre><code>EquivalentClasses(&lt;http://www.ifomis.org/bfo/1.1/spanTemporalRegion&gt; ObjectUnionOf(&lt;http://www.ifomis.org/bfo/1.1/spanScatteredTemporalRegion&gt; &lt;http://www.ifomis.org/bfo/1.1/spanConnectedTemporalRegion&gt;))
  </code></pre>
  
  <p>I tried:</p>
  
  <pre><code>content=content[content.find("ObjectUnionOf(")+1:content.find(")")]
  </code></pre>
  
  <p>but it doesn't work</p>