def test_tell(self):
        """
        C{.tell()} should return the number of bytes that have been read so
        far.
        """
        contents = "x" * 100
        with self.getFileEntry(contents) as entry:
            entry.read(2)
            self.assertEqual(entry.tell(), 2)
            entry.read(4)
            self.assertEqual(entry.tell(), 6)

        C{.tell()} should return the number of bytes that have been read so
        far.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_zipstream.py