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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def blob(self, sha):
 """Get the blob indicated by ``sha``. :param str sha: (required), sha of the blob :returns: :class:`Blob <github3.git.Blob>` if successful, otherwise None """

        url = self._build_url('git', 'blobs', sha, base_url=self._api)
        json = self._json(self._get(url), 200)
        return Blob(json) if json else None