docs: def add(self, source_id, auth, validate=True):
          """ Add one or more sets of authorization credentials to a Managed Source
  
              Uses API documented at http://dev.datasift.com/docs/api/rest-api/endpoints/sourceauthadd
  
              :param source_id: target Source ID
              :type source_id: str
              :param auth: An array of the source-specific authorization credential sets that you're adding.
              :type auth: array of strings
              :param validate: Allows you to suppress the validation of the authorization credentials, defaults to true.
              :type validate: bool
              :return: dict of REST API output with headers attached
              :rtype: :class:`~datasift.request.DictResponse`
              :raises: :class:`~datasift.exceptions.DataSiftApiException`, :class:`requests.exceptions.HTTPError`
          """
          params = {'id': source_id, 'auth': auth, 'validate': validate}
          return self.request.post('add', params)