title: flask to write data into file
body: <p>I have problem to write data into file from my flask developments server (win7), </p>
  
  <pre><code> @app.route('/')
   def main():
  
      fo = open("test.txt","wb")
      fo.write("This is Test Data")
  
   return render_template('index.html')
  </code></pre>
  
  <p>Why this don't works in flask ? </p>