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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 update(self, source_id, source_type, name, resources, auth, parameters=None, validate=True):
 """ Update a managed source Uses API documented at http://dev.datasift.com/docs/api/rest-api/endpoints/sourceupdate :param source_type: data source name e.g. facebook_page, googleplus, instagram, yammer :type source_type: str :param name: name to use to identify the managed source being created :type name: str :param resources: list of source-specific config dicts :type resources: list :param auth: list of source-specific authentication dicts :type auth: list :param parameters: (optional) dict with config information on how to treat each resource :type parameters: dict :return: dict of REST API output with headers attached :rtype: :class:`~datasift.request.DictResponse` :raises: :class:`~datasift.exceptions.DataSiftApiException`, :class:`requests.exceptions.HTTPError` """

        assert resources, "Need at least one resource"
        assert auth, "Need at least one authentication token"
        params = {'id': source_id, 'source_type': source_type, 'name': name, 'resources': resources, 'auth': auth, 'validate': validate}
        if parameters:
            params['parameters'] = parameters

        return self.request.post('update', params)