title: Selecting specific <tr> tags with BeautifulSoup
body: <p>I am fetching some html table rows with BeautifulSoup with this piece of code:</p>
  
  <pre><code>from bs4 import BeautifulSoup
  import urllib2
  import re
  
  page = urllib2.urlopen('www.something.bla')
  soup = BeautifulSoup(page)
  rows = soup.findAll('tr', attrs={'class': re.compile('class1.*')})
  </code></pre>
  
  <p>This is what I get as a result:</p>
  
  <pre><code>&lt;tr class="class1 class2 class3"&gt;...&lt;/tr&gt;
  &lt;tr class="class1 class2 class3"&gt;...&lt;/tr&gt;
  &lt;tr class="class1 class5"&gt;...&lt;/tr&gt;
  &lt;tr class="class1_a class5_a"&gt;...&lt;/tr&gt;
  &lt;tr class="class1 class5"&gt;...&lt;/tr&gt;
  &lt;tr class="class1_a class5_a"&gt;...&lt;/tr&gt;
  &lt;!-- etc. --&gt;
  </code></pre>
  
  <p>However, I'd like to exclude (or not select them in the first place) those rows which have <code>class1 class2 class3</code> as an attribute.</p>
  
  <p>How can I do that?<br>
  Thanks for help!</p>