'Get the blob indicated by ``sha``.
:param str sha: (required), sha of the blob
:returns: :class:`Blob <github3.git.Blob>` if successful, otherwise
None'

def blob(self, sha):

    url = self._build_url(u'git', u'blobs', sha, base_url=self._api)
    json = self._json(self._get(url), 200)
    return self._instance_or_null(Blob, json)
