title: How to create MediaIoBaseUpload from webapp2 request corresponding to a HTML form submission
body: <p>I have following HTML form that uploads a file to the server</p>
  
  <p>HTML:</p>
  
  <pre><code>&lt;form id="form1" enctype="multipart/form-data" method="post" action="submit"&gt;
  &lt;input type="file" name="file" accept="text/plain,text/html,application/msword,application/vnd.openxmlformats-officedocument.wordprocessingml.document"/&gt;
  &lt;div&gt;&lt;input id="submit_button" type="submit" value="Upload"/&gt;&lt;/div&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>What is the best way to create a <code>MediaIoBaseUpload</code> object on the server corresponding to the file? </p>
  
  <p>Python:    </p>
  
  <pre><code>def post(self):
          file = self.request.POST['file']                
          # How to create a MediaIoBaseUpload object from file?
  </code></pre>