human
Solve the following python programming problem given the following code:
@ mock.patch ('sahara.conductor.API.data_source_get') 
def test_get_data_sources(self, ds) : 
    def _conductor_data_source_get(ctx, id) : 
        return mock.Mock (id = id, url = ('obj_' + id)) 
(job, job_exec) = u.create_job_exec (edp.JOB_TYPE_PIG) 
    job_exec.input_id = 's1' 
    job_exec.output_id = 's2' 
    ds.side_effect = <MASK> 
    (input_source, output_source) = job_utils.get_data_sources (job_exec, job, { 
        
}) 
    self.assertEqual ('obj_s1', input_source.url) 
    self.assertEqual ('obj_s2', output_source.url) 
    
    Given the code above, what is a proper replacement for <MASK>? Choose among: self, output_source, ds, job_exec, input_source, job
assistant
#Here is a proper replacement for <MASK>.
def _conductor_data_source_get(