I\'m calling this method from the Python boto2 library:
boto.emr.step.StreamingStep(name, mapper, reducer=None, combiner=None, action_on_failure=\'TERMINATE_
Just pass the arguments you want by keyword: boto.emr.step.StreamingStep(name='a name', mapper='a mapper', combiner='a combiner')
boto.emr.step.StreamingStep(name='a name', mapper='a mapper', combiner='a combiner')