title: How to determine the Content-Length of a gzipped file in Python?
body: <p>I've a big compressed file and I want to know the size of the content without uncompress it. I've tried this:</p>
  
  <pre><code>import gzip
  import os
  
  with gzip.open(data_file) as f:
            f.seek(0, os.SEEK_END)
            size = f.tell()
  </code></pre>
  
  <p>but I get this error</p>
  
  <pre><code>ValueError: Seek from end not supported 
  </code></pre>
  
  <p>How can I do that?</p>
  
  <p>Thx.</p>