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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 list_datasources(self, source_id):
 """ Filterable list of Datasources for a Source. """

        target_url = self.client.get_url('DATASOURCE', 'GET', 'multi', {'source_id': source_id})
        return base.Query(self.client.get_manager(Datasource), target_url)