title: Google Drive API: can't read doc owned by other user
body: <p>I'm trying to read some Google Doc using the <code>gspread</code> client (Python).</p>
  <p>I have instanciated a <code>gspread.Client</code> using the scope <code>https://www.googleapis.com/auth/drive.file</code> and an oauth token for my account.</p>
  <p>I tried opening two different files, only the first one (file that I own) can be read this way.</p>
  <p>The second file (which is shared with me through a group and I can open in the web app) fails to be read:</p>
  <pre><code>&gt;&gt;&gt; gc.open_by_key(&quot;171b...&quot;) # I created this file
  &lt;Spreadsheet ...&gt;
  &gt;&gt;&gt; gc.open_by_key(&quot;1ehE...&quot;) # This file is shared with me
  gspread.exceptions.APIError: {'code': 404, 'message': 'Requested entity was not found.', 'status': 'NOT_FOUND'}
  </code></pre>
  <p>What can be the reason for that?</p>