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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 thumbprint(self, hashalg=hashes.SHA256()):
 """Returns the key thumbprint as specified by RFC 7638. :param hashalg: A hash function (defaults to SHA256) """


        t = {'kty': self._params['kty']}
        for name, val in iteritems(JWKValuesRegistry[t['kty']]):
            if val.required:
                t[name] = self._key[name]
        digest = hashes.Hash(hashalg, backend=default_backend())
        digest.update(bytes(json_encode(t).encode('utf8')))
        return base64url_encode(digest.finalize())