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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 _post_subject(self, body):
 """ Create new subjects and associated attributes. Example: acs.post_subject([ { "subjectIdentifier": "/role/evangelist", "parents": [], "attributes": [ { "issuer": "default", "name": "role", "value": "developer evangelist", } ] } ]) The issuer is effectively a namespace, and in policy evaluations you identify an attribute by a specific namespace. Many examples provide a URL but it could be any arbitrary string. The body is a list, so many subjects can be added at the same time. """

        assert isinstance(body, (list)), "POST requires body to be a list"

        uri = self._get_subject_uri()
        return self.service._post(uri, body)