title: write xml with beautiful soup
body: <p>this may be a truly stupid question but I haven't readily found the answer.
  once i modify the xml tree as necessary, how do I write it back out to file?</p>
  
  <p>code:</p>
  
  <pre><code>workbook = open("C:\\Users\\rabdel.WINCMPT\\Documents\\Retail Footwear.twb")
  soup = BeautifulSoup(workbook)
  
  for dashboard in soup.findAll("dashboard"):
      print dashboard["name"]
      if dashboard["name"] == "S1":
          dashboard.extract()
  
  for window in soup.findAll("window"):
      print "class:",window["class"]
      if "name" in [x[0] for x in window.attrs]:
          print "name:",window["name"]
          if window["name"] == "S1":
              window.extract()
  </code></pre>